Filed Pursuant to Rule 424(b)(5)
Registration Numbers: 333-235329

PROSPECTUS SUPPLEMENT

(To Prospectus dated December 16, 2019)

2,800,000 Shares

Eton Pharmaceuticals, Inc.

Pursuant to this prospectus supplement and the accompanying prospectus, we are offering 2,800,000 shares of our common stock in this offering.

Our common stock trades on the Nasdaq Global Market under the symbol “ETON.” On October 13, 2020, the last reported sale price of the common stock on the Nasdaq Global Market was $6.93 per share.

Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information under the heading “Risk Factors” beginning on page S-4 of this prospectus supplement and in the documents incorporated by reference into this prospectus supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense.

The offering is being underwritten on a firm commitment basis. We have granted the underwriter an option for a period of 45 days from the date of this prospectus supplement to purchase up to 420,000 additional shares of our common stock at the public offering price less underwriting discounts and commissions. If the underwriter exercises the option in full, the total underwriting discounts and commissions payable by us will be approximately $1.4 million and the total proceeds to us, before expenses, will be approximately $21.2 million. See “Underwriting” for more information.

The underwriter expects to deliver the shares of common stock being offered pursuant to this prospectus supplement and the accompanying prospectus on or about October 16, 2020.

Sole Book-Running Manager

National Securities Corporation

The date of this prospectus supplement is October 14, 2020

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

ABOUT THIS PROSPECTUS SUPPLEMENT

This document is in two parts. The first part is the prospectus supplement, including the documents incorporated by reference herein, which describes the specific terms of this offering and also adds to and updates the information contained in the accompanying prospectus dated December 16, 2019 and the documents incorporated by reference therein. The second part, the accompanying prospectus, including the documents incorporated by reference therein, provides more general information, some of which may not apply to this offering. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. Before you invest, you should carefully read this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein, as well as the additional information described in this prospectus supplement under “Where You Can Find More Information” and “Incorporation of Certain Information By Reference.” This prospectus supplement may add, update or change information contained in the accompanying prospectus. To the extent that any statement we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus or any documents incorporated by reference therein, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus and such documents incorporated by reference therein. However, if any statement in one of these documents is inconsistent with a statement in another document with a later date that is incorporated by reference herein, the statement in the document having the later date modifies and supersedes the earlier statement.

This prospectus supplement, together with the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus and any free writing prospectus we have provided for use in connection with this offering, include all material information relating to this offering. Neither we nor the underwriter have authorized anyone to provide you with any information or to make any representation, other than those contained or incorporated by reference in this prospectus supplement and the accompanying prospectus, which together we sometimes refer to generally as the prospectus, or in any free writing prospectus prepared by us or on our behalf or to which we have referred you. Neither we nor the underwriter take any responsibility for, and provide no assurance as to the reliability of, any other information that others may give you. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

This prospectus supplement and the accompanying prospectus contain summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the full text of the actual documents, some of which have been filed or will be filed and incorporated by reference herein. See “Where You Can Find More Information” in this prospectus supplement. We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into this prospectus supplement or the accompanying prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

This prospectus supplement and the accompanying prospectus contain and incorporate by reference certain market data and industry statistics and forecasts that are based on Company-sponsored studies, independent industry publications and other publicly available information. Although we believe these sources are reliable, estimates as they relate to projections involve numerous assumptions, are subject to risks and uncertainties, and are subject to change based on various factors, including those discussed under “Risk Factors” in this prospectus supplement and the accompanying prospectus and under similar headings in the documents incorporated by reference herein and therein. Accordingly, investors should not place undue reliance on this information.

We are offering to sell, and seeking offers to buy, shares of our common stock only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the offering of the common stock in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the distribution of this prospectus supplement outside the United States. This prospectus supplement does not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

Unless the context indicates otherwise, as used in this prospectus supplement and the accompanying prospectus, the terms “Company,” “Eton,” “we,” “us” and “our” refer to Eton Pharmaceuticals, Inc., a Delaware corporation.

This prospectus supplement, the accompanying prospectus and the information incorporated herein and therein by reference includes trademarks, service marks and trade names owned by us or other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus supplement or the accompanying prospectus are the property of their respective owners

PROSPECTUS SUPPLEMENT SUMMARY

Company Overview

We were formed in April 2017 as a specialty pharmaceutical company focused on developing and commercializing innovative pharmaceutical products. We seek to improve the formula, delivery system, or safety of existing molecules in order to address unmet patient needs. We pursue what we perceive to be low-risk product candidates where existing published literature, historical clinical trials, or physician usage has established safety and/or efficacy of the molecule, thereby reducing the incremental clinical burden required for us to bring the product to patients.

Recent Developments

In October 2019, the U.S. Food and Drug Administration (“FDA”) approved Biorphen®, and we commenced marketing Biorphen in the United States in December 2019. Biorphen (phenylephrine HCl injection) is an alpha-1 adrenergic receptor agonist indicated for the treatment of clinically important hypotension resulting primarily from vasodilation in the setting of anesthesia. We acquired U.S marketing rights to Biorphen in February 2019.

In May 2020, we were confirmed as first filer of an abbreviated new drug application for Exela Pharma Science’s Elcys cysteine hydrochloride injection formerly known as our project DS-300. Cysteine hydrochloride is an injectable product used as an additive to amino acid solutions to meet the nutritional requirements of newborn infants. Exela Pharma Science holds three patents, U.S. Patent Nos. 10,478,453, 10,653,719, and 10,583,155, that cover cysteine hydrochloride. However, in our application we challenged the validity of Exela Pharma Science’s patents. We believe that Exela Pharma Science’s patents will be invalidated, however there can be no assurance that we will be successful in our efforts to invalidate the patents.

In July 2020, we submitted our new drug application to the FDA for zonisamide oral suspension (ET-104), a treatment for partial seizures in patients with epilepsy. Zonisamide is widely used as a capsule to treat partial seizures, but the molecule is not FDA-approved in liquid form. Our patent-pending liquid formulation addresses the significant unmet need for patients with dysphagia and patients that require the precision dosing that a liquid product offers.

In September 2020, the FDA granted approval for Alaway^® Preservative Free (ketotifen fumarate) ophthalmic solution, 0.035%, antihistamine eye drops (EM-100). The solution is the first over-the-counter (OTC) preservative-free formulation eye drop approved to temporarily relieve itchy eyes due to pollen, ragweed, grass, animal hair and dander, which is one of the eye symptoms that affects approximately 80 percent of people with allergies.

In September 2020, the FDA granted approval for ALKINDI® SPRINKLE (hydrocortisone) oral granules as replacement therapy for Adrenocortical Insufficiency (AI) in children under 17 years of age. ALKINDI SPRINKLE is the first and only FDA-approved granular hydrocortisone formulation for the treatment of adrenocortical insufficiency specifically designed for use in children.

In October 2020, we submitted a new drug application to the FDA for topiramate oral solution (ET-101), seeking approval for the indications of (1) monotherapy for treatment of partial-onset or primary general tonic-clonic seizures in patients two years age and older; (2) adjunctive therapy for treatment of partial-onset seizures, including seizures associated with Lennox-Gastaut syndrome in patients two years of age and older; and (3) preventative treatment of migraine in patients 12 years of age and older.

In October 2020, the FDA accepted our new drug application for orphan drug dehydrated alcohol injection (DS-100). We previously received orphan drug designation for the treatment of methanol poisoning, and we expect to receive seven years of market exclusivity upon its approval. The application has been assigned a Prescription Drug User Fee Act dated as of May 27, 2021. The U.S. market for dehydrated alcohol injection is estimated to be greater than $100 million annually and the drug is currently only supplied by a single manufacturer.¹

We believe we have established a diversified pipeline of product candidates in various stages of development, including multiple candidates that have been submitted to the FDA for review. Our product candidates are primarily focused on two core areas: hospital-based products and pediatric rare disease products. We believe these candidates can address situations where patient needs are not being met by current FDA-approved products.

Corporate Information

We were incorporated under the laws of the state of Delaware in April 2017. Our principal executive offices are located at 21925 W. Field Parkway, Suite 235, Deer Park, Illinois, 60010, and our telephone number is (847) 787-7361. Our corporate website address is www.etonpharma.com, to which we regularly post copies of our press releases as well as links to reports we have filed with the SEC, which are available free of charge as soon as reasonably practicable after being electronically filed with or furnished to the SEC. Interested persons can subscribe on our website to email alerts that are sent automatically when we issues press releases, file reports with the SEC or post certain other information to our website. We do not incorporate the information on our website into this prospectus supplement or the accompanying prospectus and you should not consider it part of this prospectus supplement or the accompanying prospectus.

Qualified Small Business Stock

We believe that upon the close of this offering (i) we will be  an “eligible corporation” as defined in Section 1202(e)(4) of the Internal Revenue Code of 1986, as amended, or Code, (ii) we will not have made any purchases of our own stock during the one-year period preceding the closing having an aggregate value exceeding 5% of the aggregate value of all our stock as of the beginning of such period and (iii) our aggregate gross assets, as defined by Code Section 1202(d)(2), at no time and through the closing will have exceeded or will exceed $50 million, taking into account the assets of any corporations required to be aggregated with us in accordance with Code Section 1202(d)(3).  As such, we believe that the common stock offered hereby will be “qualified small business stock” pursuant to Code Section 1202(c).  Please note, however, that we have not obtained the opinion of tax counsel with regard to this matter and investors are encouraged to consult with their own tax advisors with regard to the applicability or interpretation of Code Section 1202.

¹ Based on IQVIA data’s average of 130,928 units annually from 2016-2019 and the current market WAC price of $995 per unit.

THE OFFERING

The number of shares of common stock that will be issued and outstanding immediately after this offering is based on 20,956,033 shares of common stock issued and outstanding as of June 30, 2020 and excludes, as of that date, the following:

Except as otherwise indicated, all information in this prospectus supplement assumes no exercise of outstanding options and warrants and no exercise of the underwriter’s option to purchase additional shares of common stock.to purchase additional shares of common stock.

RISK FACTORS

An investment in our securities involves a high degree of risk. Prior to making a decision about investing in our securities, you should carefully consider the risk factors described below together with all of the risks, uncertainties and assumptions described in our Annual Report on Form 10-K for the year ended December 31, 2019, as amended and our Quarterly Reports on Form 10-Q for the quarters ended March 31 and June 30, 2020, which are incorporated herein by reference, and may be amended, supplemented or superseded from time to time by other reports we subsequently filed with the Securities and Exchange Commission, or SEC. If any of the risks incorporated by reference or set forth below occurs, our business, operations and financial condition could suffer significantly. As a result, you could lose some or all of your investment in our common stock. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our business, operations and financial condition, or cause the value of our common stock to decline.

Risks related to COVID-19

Our business is adversely affected by the ongoing coronavirus pandemic and the impact could be material.

The global COVID-19 pandemic has resulted in widespread requirements for individuals to stay in their homes and strained medical facilities worldwide, including certain aspects of our business. For example, we began commercializing our Biorphen product in December 2019, however we have encountered difficulty in creating significant market pull-through demand for Biorphen in 2020 as our in-person sales calls to key personnel at hospitals and surgical centers and introductory product presentation seminars were cancelled as a result of the COVID-19 pandemic. We are working on other promotional efforts to drive further adoption in the market, but we expect that our Biorphen sales and marketing efforts will continue to be adversely affected by the pandemic in 2020.  COVID-19 may also affect our ability to complete recruitment and data analysis for our clinical trials and our ability to conduct research and development of our complement programs in our planned timeframe. The extent to which COVID-19 impacts our operations will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration and severity of the outbreak, and the actions that may be required to contain COVID-19 or treat its impact. In particular, as a result of the COVID-19 pandemic, we may experience disruptions that could severely impact our business, preclinical studies, drug manufacturing and clinical trials including:

Risks related to this offering

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management has broad discretion in the application of the net proceeds from this offering, and you will not have the opportunity as part of your investment decision to assess whether the net proceeds are being used appropriately. Our management could spend the net proceeds from this offering in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our product candidates. Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

If you purchase shares of common stock sold in this offering you will experience immediate and substantial dilution in your investment. You will experience further dilution if we issue additional equity securities in the future.

Since the price per share of our common stock being offered is higher than the net tangible book value per share of our common stock, you will suffer dilution with respect to the net tangible book value of the shares of common stock you purchase in this offering. Based on a public offering price of $7.00 per share and our net tangible book value as of June 30, 2020, if you purchase shares of common stock in this offering, you will suffer immediate dilution of $5.96 per share with respect to the net tangible book value of the common stock. Furthermore, if outstanding options or warrants are exercised, you could experience further dilution. See “Dilution” for a more detailed discussion of the dilution you will incur if you purchase shares of common stock in this offering.

Future sales of our common stock in the public market could cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock and make it more difficult for you to sell your common stock at a time and price that you deem appropriate.

We may raise money through additional public or private offerings of our equity securities or equity-linked securities. Any sales of our equity or equity-linked securities could have a material adverse effect on the market price of our common stock.

We have registered under the Securities Act of 1933, as amended (“Securities Act”) 3,500,000 shares of common stock held by our former parent, Harrow Health, Inc., which enables Harrow to sell some or all of such shares without restriction. While Harrow has entered into a “lock-up agreement” with us whereby it has agreed not to sell any such shares without our prior approval, the lock-up agreement expires on the close of this offering. We have also registered under the Securities Act 6,419,416 shares of our common stock and as of October 13, 2020, 443,246 shares of our common stock remain available under our Incentive Plan. In addition, we have a significant number of stock options outstanding, and may also choose to issue additional common stock, or securities convertible into or exchangeable for common stock, in the future in connection with a financing, an acquisition, a litigation settlement, employee arrangements or otherwise, such issuances could reduce the market price of our common stock and make it more difficult for you to sell your common stock at a time and price that you deem appropriate. In addition, in the event that the outstanding options are exercised, or that we make additional issuances of common stock or other convertible or exchangeable securities, you could experience additional dilution. Furthermore, we cannot assure you that we will be able to issue shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing our securities in the future may have rights superior to investors purchasing shares in this offering.

We do not anticipate paying dividends on our common stock in the foreseeable future.

We currently plan to invest all available funds, including the proceeds from this offering, and future earnings, if any, in the development and growth of our business. We currently do not anticipate paying any cash dividends on our common stock in the foreseeable future. As a result, a rise in the market price of our common stock, which is uncertain and unpredictable, will be your sole source of potential gain in the foreseeable future, and you should not rely on an investment in our common stock for dividend income.

CAUTIONARY NOTE REGARDING FORWARD LOOKING INFORMATION

This prospectus supplement, the accompanying prospectus, and documents incorporated by reference herein and therein contain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve a number of risks and uncertainties. We caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from those contained in the forward-looking statement. These statements are based on current expectations of future events. Such statements include, but are not limited to, statements about future financial and operating results, plans, objectives, expectations and intentions, costs and expenses, outcome of contingencies, financial condition, results of operations, liquidity, objectives of management, business strategies, financing, the timing, plans and expected results of our current and future clinical trials, the extent to which we will be able to advance development of our product candidates using the proceeds of this offering together with our existing cash resources; our focus on specific product candidates, the progress, outcomes, scope or duration of the development of product candidates or programs, the benefits that may be derived from product candidates or the commercial or market opportunity in any target indication, the progress of our third-party collaborations, including estimated milestones, the advancement of our technologies and our product candidates, approvals and commercialization of product candidates, the impacts of the COVID-19 pandemic and other statements that are not historical facts. You can find many of these statements by looking for words like “believes,” “expects,” “anticipates,” “estimates,” “may,” “might,” “should,” “will,” “could,” “plan,” “intend,” “project,” “seek” or similar expressions in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein and any free writing prospectus. We intend that such forward-looking statements be subject to the safe harbors created thereby.

These forward-looking statements are based on the current beliefs and expectations of our management and are subject to significant risks and uncertainties. If underlying assumptions prove inaccurate or unknown risks or uncertainties materialize, actual results may differ materially from current expectations and projections. Factors that might cause such a difference include those discussed in the Risk Factors sections of our Annual Report on Form 10-K for the year ended December 31, 2019, as filed with the SEC on March 5, 2020, as amended by Form 10-K/A, as filed with the SEC on May 21, 2020 and our Quarterly Reports on Form 10-Q for the quarters ended March 31 and June 30, 2020, as well as those discussed in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein and any free writing prospectus. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date made.

All subsequent written or oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this prospectus supplement or to reflect the occurrence of unanticipated events, except as may be required under applicable U.S. securities laws. If we do update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

USE OF PROCEEDS

We expect that the net proceeds of this offering, after deducting underwriting discounts and commissions and estimated offering expenses, will be approximately $18.3 million, or approximately $21.0 million if the underwriter exercises its over-allotment option in full.

We intend to use the net proceeds from the sale of the shares of common stock under this prospectus supplement for general corporate purposes, which may include research and development activities, capital expenditures, selling, general and administrative costs, facilities expansion, and to meet working capital needs. We expect from time to time to evaluate the acquisition of businesses, products and technologies for which a portion of the net proceeds may be used, although we currently are not planning or negotiating any such transactions.

As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses of the proceeds from this offering. The amounts and timing of our actual expenditures will depend on numerous factors, including the progress of our clinical trials and other development efforts and other factors described under “Risk factors” in this prospectus supplement and the documents incorporated by reference herein. As a result, our management will have broad discretion over the uses of the net proceeds we receive in connection with securities offered pursuant to this prospectus supplement and investors will be relying on the judgment of our management regarding the application of the proceeds. Pending these uses, we intend to invest the net proceeds in short-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or guaranteed obligations of the U.S. government.

DILUTION

If you invest in our common stock, your interest will be diluted immediately to the extent of the difference between the public offering price per share of our common stock and the as adjusted net tangible book value per share of common stock after this offering.

Our net tangible book value as of June 30, 2020 was approximately $6.4 million, or approximately $0.30 per share. Net tangible book value per share is determined by dividing our total tangible assets, less total liabilities, by the number of shares of our common stock outstanding as of June 30, 2020.

After giving effect to our sale of shares of our common stock in this offering at the public offering price of $7.00 per share, and after deducting the underwriting discount and commissions and the estimated offering expenses payable by us, our as adjusted net tangible book value as of June 30, 2020 would have been approximately $ 24.7 million, or $1.04 per share of common stock. This represents an immediate increase in net tangible book value of $0.74 per share to existing stockholders and an immediate dilution in net tangible book value of $5.96 per share to investors participating in this offering. The following table illustrates this dilution on a per share basis:

If the underwriter exercises in full its option to purchase 420,000 additional shares of common stock at the public offering price of $7.00 per share, the as adjusted net tangible book value after this offering would have been approximately $27.4 million or $1.13 per share, representing an increase in net tangible book value of approximately $0.83 per share to existing stockholders and immediate dilution in net tangible book value of approximately $5.87 per share to investors participating in this offering at the public offering price.

The number of shares of common stock that will be issued and outstanding immediately after this offering is based on 20,956,033 shares of common stock issued and outstanding as of June 30, 2020 and excludes, as of that date, the following:

Except as otherwise indicated, all information in this prospectus supplement assumes no exercise of outstanding options and warrants and no exercise of the underwriter’s option to purchase additional shares of common stock to purchase additional shares of common stock.

To the extent that outstanding options have been or may be exercised or other shares are issued, investors purchasing our common stock in this offering may experience further dilution. In addition, we may choose to issue additional common stock, or securities convertible into or exchangeable for common stock, in the future. The issuance of these securities could result in further dilution for investors purchasing our common stock in this offering.

UNDERWRITING

We have entered into an underwriting agreement with National Securities Corporation, who we refer to as the underwriter, dated October 14, 2020. Subject to the terms and conditions of the underwriting agreement, we have agreed to sell to the underwriter the 2,800,000 shares of common stock offered hereby, and the underwriter has agreed to purchase, at the public offering price, less the underwriting discount set forth on the cover page of this prospectus supplement, such shares.

The underwriter is committed to purchase all the shares of common stock offered by us other than those covered by the option to purchase additional shares described below. The obligation of the underwriter may be terminated upon the occurrence of certain events specified in the underwriting agreement. Furthermore, pursuant to the underwriting agreement, the underwriter’s obligation is subject to customary conditions, representations and warranties contained in the underwriting agreement, such as receipt by the underwriter of officers’ certificates and legal opinions.

We have agreed to indemnify the underwriter against specified liabilities, including liabilities under the Securities Act, and to contribute to payments the underwriter may be required to make in respect thereof. The underwriter is offering the shares, subject to prior sale, when, as and if issued to and accepted by it, subject to approval of legal matters by its counsel and other conditions specified in the underwriting agreement. The underwriter reserves the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

The underwriter proposes to offer the shares of common stock to the public at the public offering price set forth on the cover page of this prospectus supplement. In addition, the underwriter may offer some of the shares of common stock to other securities dealers at such price less a concession of $0.231 per share. If all of the shares of common stock are not sold at the public offering price, the underwriter may change the offering price and other selling terms by means of a further supplement to this prospectus supplement.

We have granted the underwriter an over-allotment option. This option, which is exercisable for up to 45 days after the closing date of this offering, permits the underwriter to purchase a maximum of 420,000 additional shares of common stock from us to cover over-allotments, if any. If the underwriter exercises all or part of this option, it will purchase shares covered by the option at the public offering price that appears on the cover page of this prospectus supplement, less the underwriting discount. If this option is exercised in full, the total price to the public will be approximately $22.5 million and the total proceeds to us, before expenses, will be approximately $21.2 million.

Discount. The following table shows the public offering price, underwriting discount and proceeds, before expenses, to us. The information assumes either no exercise or full exercise by the underwriter of its over-allotment option.

We expect that the total offering expenses payable by us, including a non-accountable expense allowance payable to the underwriter of $65,000 will be approximately $144,000.

Discretionary Accounts. The underwriter does not intend to confirm sales of the common stock offered hereby to any accounts over which it has discretionary authority.

Electronic Offer, Sale and Distribution of Shares. A prospectus supplement in electronic format may be made available on the websites maintained by the underwriter, and the underwriter may distribute prospectus supplements electronically. Other than the prospectus supplement in electronic format, the information on these websites is not part of this prospectus supplement or the registration statement of which this prospectus supplement forms a part, has not been approved or endorsed by us or the underwriter in its capacity as underwriter, and should not be relied upon by investors.

Other Relationships. The underwriter and its affiliates may in the future provide various investment banking, commercial banking and other financial services for us and our affiliates for which they may receive customary fees; however, except as disclosed in this prospectus supplement, we have no present arrangements with the underwriter for any further services.

Stabilization. In connection with this offering, the underwriter may engage in stabilizing transactions, over-allotment transactions, syndicate covering transactions, penalty bids and purchases to cover positions created by short sales.

● Stabilizing transactions permit bids to purchase shares so long as the stabilizing bids do not exceed a specified maximum, and are engaged in for the purpose of preventing or retarding a decline in the market price of the shares while the offering is in progress.

● Over-allotment transactions involve sales by the underwriter of shares in excess of the number of shares the underwriter is obligated to purchase. This creates a syndicate short position which may be either a covered short position or a naked short position. In a covered short position, the number of shares over-allotted by the underwriter is not greater than the number of shares that they may purchase in the over-allotment option. In a naked short position, the number of shares involved is greater than the number of shares in the over-allotment option. The underwriter may close out any short position by exercising its over-allotment option and/or purchasing shares in the open market.

● Syndicate covering transactions involve purchases of shares in the open market after the distribution has been completed in order to cover syndicate short positions. In determining the source of shares to close out the short position, the underwriter will consider, among other things, the price of shares available for purchase in the open market as compared with the price at which they may purchase shares through exercise of the over-allotment option. If the underwriter sells more shares than could be covered by exercise of the over-allotment option and, therefore, have a naked short position, the position can be closed out only by buying shares in the open market. A naked short position is more likely to be created if the underwriter is concerned that, after pricing, there could be downward pressure on the price of the shares in the open market, which could adversely affect investors who purchase in the offering.

● Penalty bids permit the underwriter to reclaim a selling concession from a syndicate member when the shares originally sold by that syndicate member are purchased in stabilizing or syndicate covering transactions to cover syndicate short positions.

These stabilizing transactions, syndicate covering transactions and penalty bids may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock in the open market may be higher than it would otherwise be in the absence of these transactions. Neither we nor the underwriter make any representation or prediction as to the effect that the transactions described above may have on the price of our common stock. These transactions may be effected on the Nasdaq Global Market, in the over-the-counter market or otherwise and, if commenced, may be discontinued at any time.

Passive Market Making. In connection with this offering, the underwriter may engage in passive market making transactions in our common stock on the Nasdaq Capital Market in accordance with Rule 103 of Regulation M under the Securities Exchange Act of 1934 (“Exchange Act”) during a period before the commencement of offers or sales of the shares and extending through the completion of the distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded.

Offer restrictions outside the United States

Other than in the United States, no action has been taken by us or the underwriter that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement and the accompanying prospectus may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

LEGAL MATTERS

The validity of the securities being offered by this prospectus will be passed upon by Croke Fairchild Morgan & Beres LLC, Chicago, Illinois. The underwriter is being represented in connection with this offering by Greenberg Traurig, LLP, Irvine, California.

EXPERTS

The financial statements of the Company as of December 31, 2019 and 2018, and for the years then ended and the period from April 27, 2017 (inception) to December 31, 2017 that are incorporated by reference into this prospectus supplement, have been so incorporated in reliance upon the report of KMJ Corbin & Company LLP, an independent registered public accounting firm, incorporated by reference herein, given the authority of said firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the securities offered hereby. This prospectus supplement, which constitutes a part of the registration statement, does not contain all of the information set forth in the registration statement or the exhibits filed therewith. For further information about us and the securities offered hereby, reference is made to the accompanying prospectus and registration statement of which it is a part and the exhibits filed therewith.

We are subject to the informational requirements of the Exchange Act and are required to file annual, quarterly and other reports, proxy statements and other information with the SEC. You may read and copy any document that we file at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the Public Reference Room. The SEC also maintains an Internet site (http://www.sec.gov) that contains reports, proxy and information statements, and various other information about us.

Certain information filed by us with the SEC is also available at our website at www.etonpharma.com. However, the information on our website is not a part of this prospectus supplement and is not incorporated by reference into this prospectus supplement.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

This prospectus supplement and the accompanying prospectus “incorporate by reference” information that we have filed with the SEC under the Exchange Act. This means that we are disclosing important information to you by referring you to those documents. Information contained in any document subsequently filed with the SEC, to the extent it modifies information in this prospectus supplement, in the accompanying prospectus or in any document incorporated by reference in this prospectus supplement or the accompanying prospectus, will automatically update and supersede the information originally included in this prospectus supplement, the accompanying prospectus or any document incorporated by reference in this prospectus supplement or the accompanying prospectus.

We incorporate by reference the following documents that we previously filed with the SEC pursuant to the Securities Act or the Exchange Act and any future filings we will make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the time that all securities covered by this prospectus supplement have been sold; provided, however, that we are not incorporating any information furnished to, rather than filed with, the SEC:

(a) Annual Reports on Form 10-K for the fiscal year ended December 31, 2019, as filed with the SEC on March 5, 2020, as amended by Form 10-K/A, as filed with the SEC on May 21, 2020;

(b) Quarterly Reports on Form 10-Q for the quarter ended March 31, 2020, as filed with the SEC on May 14, 2020, and for the quarter ended June 30, 2020, as filed with the SEC on August 12, 2020;

(c) Current Reports on Form 8-K, filed with the SEC on January 21, 2020 (with respect to Items 8.01 and 9.01), February 19, 2020 (with respect to Items 8.01 and 9.01), March 17, 2020 (with respect to Items 8.01 and 9.01), March 18, 2020 (with respect to Item 8.01), March 30, 2020 (with respect to Items 1.01, 3.02, 8.01 and 9.01), May 4, 2020 (with respect to Items 8.01 and 9.01), May 6, 2020 (with respect to Items 1.01, 2.03 and 9.01), May 7, 2020 (with respect to Items 8.01 and 9.01), June 10, 2020 (with respect to Item 5.07), July 27, 2020 (with respect to Items 8.01 and 9.01), July 30, 2020 (with respect to Items 8.01 and 9.01), July 31, 2020 (with respect to Item 8.01), August 11, 2020 (with respect to Items 8.01 and 9.01), August 31, 2020 (with respect to Items 8.01 and 9.01), September 16, 2020 (with respect to Items 8.01 and 9.01), September 25, 2020 (with respect to Items 8.01 and 9.01), September 30, 2020 (with respect to Items 8.01 and 9.01), October 6, 2020 (with respect to Items 8.01 and 9.01) and October 8, 2020 (with respect to Items 8.01 and 9.01); and

(d) The description of our common stock contained in the Company’s Registration Statement on Form 8-A filed with the SEC on November 8, 2018, pursuant to Section 12(b) of the Exchange Act, including any amendments or reports filed for the purpose of updating such description.

Any statement contained in this prospectus supplement or the accompanying prospectus or in a document incorporated or deemed to be incorporated by reference into this prospectus supplement will be deemed to be modified or superseded for purposes hereof to the extent that a statement contained in this prospectus supplement or the accompanying prospectus or any other subsequently filed document that is deemed to be incorporated by reference into this prospectus supplement modifies or supersedes the statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement and the accompanying prospectus.

The documents incorporated by reference in this prospectus supplement may be obtained from us without charge and will be provided to each person, including any beneficial owner, to whom a prospectus supplement is delivered. You may obtain a copy of the documents at no cost by submitting a written request to 21925 W. Field Parkway, Suite 235, Deer Park, Illinois, 60010, or through our telephone number at (847) 787-7361. Further information can be obtained through our website address, www.etonpharma.com. Such additional information contained in our website is not a part of this prospectus supplement.

PROSPECTUS

Eton Pharmaceuticals, Inc.

$100,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Subscription Rights

Units

We may offer and sell, from time to time in one or more offerings, any combination of common stock, preferred stock, debt securities, warrants, subscription rights or units having a maximum aggregate offering price of $100,000,000. When we decide to sell a particular class or series of securities, we will provide specific terms of the offered securities in a prospectus supplement.

The prospectus supplement may also add, update or change information contained in or incorporated by reference into this prospectus. However, no prospectus supplement shall offer a security that is not registered and described in this prospectus at the time of its effectiveness. You should read this prospectus and any prospectus supplement, as well as the documents incorporated by reference or deemed to be incorporated by reference into this prospectus or a prospectus supplement, carefully before you invest. This prospectus may not be used to offer or sell our securities unless accompanied by a prospectus supplement relating to the offered securities.

Our common stock is traded on the Nasdaq Global Market under the symbol “ETON.” Each prospectus supplement will contain information, where applicable, as to our listing on the Nasdaq Global Market or any other securities exchange of the securities covered by the prospectus supplement.

These securities may be sold directly by us, through dealers or agents designated from time to time, to or through underwriters or through a combination of these methods. See “Plan of Distribution” in this prospectus. We may also describe the plan of distribution for any particular offering of our securities in a prospectus supplement. If any agents, underwriters or dealers are involved in the sale of any securities in respect of which this prospectus is being delivered, we will disclose their names and the nature of our arrangements with them in a prospectus supplement. The net proceeds we expect to receive from any such sale will also be included in a prospectus supplement.

As of November 27, 2019, the aggregate market value of our common stock held by non-affiliates was approximately $77.6 million based on 17,807,167 outstanding shares of common stock, of which 12,271,173 shares are held by non-affiliates, and a price of $6.32 per share, which was the last reported sale price of our common stock on the Nasdaq Global Market on that date.

We were incorporated under the laws of Delaware in April 2017. Our principal executive offices are located at 21925 W. Field Parkway, Suite 235, Deer Park, Illinois, 60010, and our telephone number is (847) 787-7361.

This prospectus may not be used to offer or sell any securities unless accompanied by a prospectus supplement.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties referenced under the heading “Risk Factors” on page 2 of this prospectus as well as those contained in the applicable prospectus supplement and any related free writing prospectus, and in the other documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is December 16, 2019

TABLE OF CONTENTS

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the sections entitled “Prospectus Summary,” “Risk Factors,” “Use of Proceeds,” contains forward-looking statements. The words “believe,” “may,” “will,” “potentially,” “estimate,” “continue,” “anticipate,” “intend,” “could,” “would,” “project,” “plan,” “expect” and similar expressions that convey uncertainty of future events or outcomes are intended to identify forward-looking statements. These forward-looking statements include, but are not limited to, statements concerning the following:

These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those described in “Risk Factors” and elsewhere in this prospectus. Moreover, we operate in a very competitive and rapidly changing environment, and new risks emerge from time to time. It is not possible for us to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this prospectus may not occur and actual results could differ materially and adversely from those anticipated or implied in our forward-looking statements.

You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in our forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances described in the forward-looking statements will be achieved or occur. Moreover, neither we nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements. We undertake no obligation to update publicly any forward-looking statements for any reason after the date of this prospectus to conform these statements to actual results or to changes in our expectations, except as required by law.

You should read this prospectus and the documents that we reference in this prospectus and have filed with the Securities and Exchange Commission (“SEC”) as exhibits to the registration statement of which this prospectus is a part with the understanding that our actual future results, levels of activity, performance and events and circumstances may be materially different from what we expect.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the SEC using a “shelf” registration process. Under this shelf registration process, we may offer from time to time securities having a maximum aggregate offering price of $100,000,000. Each time we offer securities, we will prepare and file with the SEC a prospectus supplement and/or a free writing prospectus (collectively referred to herein as a “prospectus supplement”) that describes the specific amounts, prices and terms of the securities we offer. The prospectus supplement also may add, update or change information contained in this prospectus or the documents incorporated herein by reference. You should read carefully both this prospectus and any prospectus supplement together with additional information described below under the caption “Where You Can Find Additional Information About Us.”

This prospectus does not contain all the information provided in the registration statement we filed with the SEC. For further information about us or our securities offered hereby, you should refer to that registration statement, which you can obtain from the SEC as described below under “Where You Can Find Additional Information About Us.”

You should rely only on the information contained or incorporated by reference in this prospectus or any prospectus supplement. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus is not an offer to sell securities, and it is not soliciting an offer to buy securities, in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus or any prospectus supplement, as well as information we have previously filed with the SEC and incorporated by reference, is accurate as of the date of those documents only. Our business, financial condition, results of operations and prospects may have changed since those dates.

We may sell securities through underwriters or dealers, through agents, directly to purchasers or through any combination of these methods. We and our agents reserve the sole right to accept or reject in whole or in part any proposed purchase of securities. The prospectus supplement, which we will prepare and file with the SEC each time we offer securities, will set forth the names of any underwriters, agents or others involved in the sale of securities, and any applicable fee, commission or discount arrangements with them. See “Plan of Distribution.”

As used, or incorporated by reference, in this prospectus, unless otherwise stated or the context requires otherwise, the “Company” and terms such as “we,” “us” “our,” and “Eton” refer to Eton Pharmaceuticals, Inc, a Delaware corporation.

PROSPECTUS SUMMARY

The following summary, because it is a summary, may not contain all the information that may be important to you. This prospectus incorporates important business and financial information about Eton that is not included in, or delivered with, this prospectus. Before making an investment, you should read the entire prospectus and any amendment carefully. You should also carefully read the risks of investing discussed under “Risk Factors” and the financial statements included in our other filings with the SEC, including in our most recent Annual Report on Form 10-K which we filed with the SEC on March 25, 2019. This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information About Us.”

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, a copy of any or all of the information that has been incorporated by reference in this prospectus but not delivered with this prospectus. You may request a copy of these filings, excluding the exhibits to such filings which we have not specifically incorporated by reference in such filings, at no cost, by writing us at the following address: 21925 W. Field Parkway, Suite 235, Deer Park, Illinois, 60010.

Our Company

We were formed in April 2017 as a specialty pharmaceutical company focused on developing and commercializing innovative pharmaceutical products. We seek to improve the formula, delivery system, or safety of existing molecules in order to address unmet patient needs. We pursue what we perceive to be low-risk candidates where existing published literature, historical clinical trials, or physician usage has established safety and/or efficacy of the molecule, thereby reducing the incremental clinical burden required for us to bring the product to patients.

In October 2019, we received FDA approval for Biorphen® which we will market in the United States. Biorphen (phenylephrine HCl injection) is an alpha-1 adrenergic receptor agonist indicated for the treatment of clinically important hypotension resulting primarily from vasodilation in the setting of anesthesia. We acquired U.S marketing rights to Biorphen in February 2019.

We have established a diversified pipeline of product candidates in various stages of development, including multiple candidates that have been submitted to the FDA for review. Our product candidates are primarily focused on two core areas: hospital-based products and pediatric oral liquid products. We believe these candidates can address situations where patient needs are not being met by current FDA-approved products.

The Offering

This prospectus is part of a registration statement that we filed with the SEC utilizing a shelf registration process. Under this shelf registration process, we may sell any combination of:

in one or more offerings up to a total dollar amount of $100 million. This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that specific offering and include a discussion of any risk factors or other special considerations that apply to those securities. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with the additional information described under the heading “Where You Can Find Additional Information About Us.”

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information About Us.”

RISK FACTORS

Investing in our securities involves a high degree of risk. Before purchasing our securities, you should carefully consider the risks and uncertainties set forth below and under the heading “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018, which we filed with the SEC on March 25, 2019, which is incorporated by reference in this prospectus, as well as any updates thereto contained in subsequent filings with the SEC or any applicable prospectus supplement Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. Additional risk factors may be included in a prospectus supplement for a particular offering of securities.

Risks Related to Our Common Stock and the Offering

Future sales or other dilution of our equity could depress the market price of our common stock.

Our common stock is listed on the Nasdaq Global Market. However, trading volume has been limited and a more active public market for our common stock may not develop or be sustained over time. The market price of our common stock could be subject to significant fluctuations. The price of our stock may change in response to variations in our operating results and also may change in response to other factors, including factors specific to companies in our industry many of which are beyond our control. Our shares may be less liquid than the shares of other public companies and there may be imbalances between supply and demand for our shares. As a result, our share price may experience significant volatility and may not necessarily reflect the value of our expected performance. Moreover, sales of our common stock in the public market, or the perception that such sales could occur, could negatively impact the price of our common stock. As a result, you may not be able to sell your shares of our common stock in short time periods, or possibly at all, and the price per share of our common stock may fluctuate significantly.

In addition, the issuance of additional shares of our common stock pursuant to this prospectus, or issuances of securities convertible into or exercisable for our common stock or other equity-linked securities, including preferred stock, warrants, debt securities or units, would dilute the ownership interest of our common shareholders and could depress the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities.

We expect to seek to raise additional capital. If this additional financing is obtained through the issuance of equity securities, debt convertible into equity or options or warrants to acquire equity securities, our existing shareholders could experience significant dilution upon the issuance, conversion or exercise of such securities.

Our management will have broad discretion over the use of the proceeds we receive from the sale of our securities pursuant to this prospectus and might not apply the proceeds in ways that increase the value of your investment.

Our management will have broad discretion to use the net proceeds from any offerings under this prospectus, and you will be relying on the judgment of our management regarding the application of these proceeds. Except as described in any prospectus supplement (including any related free-writing prospectus) that we may authorize to be provided to you, the net proceeds received by us from our sale of the securities described in this prospectus will be added to our general funds and will be used for our general corporate purposes. Our management might not apply the net proceeds from the offering of our securities in ways that increase the value of your investment and might not be able to yield a significant return, if any, on any investment of such net proceeds. You may not have the opportunity to influence our decisions on how to use such proceeds.

USE OF PROCEEDS

Except as may be stated in the applicable prospectus supplement, we intend to use the net proceeds we receive from the sale of the securities offered by this prospectus for business expansion and general corporate purposes, which may include, among other things, repayment of debt, capital expenditures, the financing of possible acquisitions or in-licensing of additional product candidates, increasing our working capital and the financing of ongoing operating expenses and overhead. Pending the application of the net proceeds, we may invest the proceeds in marketable securities and short-term investments.

DILUTION

We will set forth in a prospectus supplement the following information regarding any material dilution of the equity interests of investors purchasing securities in an offering under this prospectus:

DESCRIPTIONS OF THE SECURITIES WE MAY OFFER

The descriptions of the securities contained in this prospectus, together with any applicable prospectus supplement, summarize all the material terms and provisions of the various types of securities that we may offer. We will describe in the applicable prospectus supplement relating to a particular offering the specific terms of the securities offered by that prospectus supplement. We will indicate in the applicable prospectus supplement if the terms of the securities differ from the terms we have summarized below. We will also include in the prospectus supplement information, where applicable, material United States federal income tax considerations relating to the securities.

We may sell from time to time, in one or more offerings:

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

CAPITAL STOCK

General

As of November 27, 2019, our authorized capital stock consists of 50,000,000 shares of common stock, par value $0.001 per share, of which 17,807,167 shares are issued and outstanding, held of record by approximately 18 stockholders, and 10,000,000 shares of preferred stock, par value $0.001 per share, of which none are issued and outstanding. The following description summarizes the most important terms of our capital stock. Because it is only a summary, it does not contain all the information that may be important to you. For a complete description, you should refer to our Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws and to the applicable provisions of Delaware law.

The authorized and unissued shares of common stock and preferred stock are available for issuance without further action by our stockholders, unless such action is required by applicable law or the rules of any stock exchange on which our securities may be listed. Unless approval of our stockholders is so required, our board of directors will not seek stockholder approval for the issuance and sale of our common stock or our preferred stock.

Common Stock

Holders of shares of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders generally. Stockholders are entitled to receive such dividends as may be declared from time to time by the board of directors out of funds legally available therefor, and in the event of liquidation, dissolution or winding up of the company to share ratably in all assets remaining after payment of liabilities. The holders of shares of common stock have no preemptive, conversion, subscription or cumulative voting rights.

Preferred Stock

Our Amended and Restated Certificate of Incorporation authorizes the issuance of preferred stock (“Preferred Stock”) from time to time in one or more series. The Board of Directors of the Company (the “Board of Directors”) is hereby expressly authorized to provide for the issue of any or all of the unissued and undesignated shares of the Preferred Stock in one or more series, and to fix the number of shares and to determine or alter for each such series, such voting powers, full or limited, or no voting powers, and such designation, preferences, and relative, participating, optional, or other rights and such qualifications, limitations, or restrictions thereof, as shall be stated and expressed in the resolution or resolutions adopted by the Board of Directors providing for the issuance of such shares and as may be permitted by the Delaware General Corporation Law (“DGCL”). The Board of Directors is also expressly authorized to increase or decrease the number of shares of any series subsequent to the issuance of shares of that series, but not below the number of shares of such series then outstanding. In case the number of shares of any series shall be decreased in accordance with the foregoing sentence, the shares constituting such decrease shall resume the status that they had prior to the adoption of the resolution originally fixing the number of shares of such series. The number of authorized shares of Preferred Stock may be increased or decreased (but not below the number of shares thereof then outstanding) by the affirmative vote of the holders of a majority of the voting power of the stock of the Company entitled to vote thereon, without a separate vote of the holders of the Preferred Stock, or of any series thereof, unless a vote of any such holders is required pursuant to the terms of any certificate of designation filed with respect to any series of Preferred Stock.

If the Preferred Stock contains any restriction on the repurchase or redemption of shares by the registrant while there is any arrearage in the payment of dividends or sinking fund installments, such restrictions will be described in the prospectus supplement.

Transfer Agent and Registrar; Market

The transfer agent and registrar for our common stock is Computershare Investor Services. Its address is 462 S. Fourth Street, Suite 1600, Louisville, KY 40202 and its telephone number is (800) 962-4284. Our common stock is listed on the Nasdaq Global Market under the symbol “ETON.”

See “Where You Can Find Additional Information About Us” elsewhere in this prospectus for information on where you can obtain copies of our Amended and Restated Certificate of Incorporation and our Amended and Restated Bylaws, which have been filed with and are publicly available from the SEC.

WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplement, summarizes the material terms and provisions of the warrants that we may offer under this prospectus and any related warrant agreements and warrant certificates. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the specific terms of any series of warrants in more detail in the applicable prospectus supplement. If we indicate in the prospectus supplement, the terms of any warrants offered under that prospectus supplement may differ from the terms described below. Specific warrant agreements will contain additional important terms and provisions and will be incorporated by reference as an exhibit to the registration statement which includes this prospectus.

General

We may issue warrants for the purchase of common stock, preferred stock and debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and debt securities, and the warrants may be attached to or separate from these securities.

We may evidence each series of warrants by warrant certificates that we may issue under a separate agreement. We may enter into a warrant agreement with a warrant agent. Each warrant agent may be a bank, transfer agent or trust company that we select which has its principal office in the United States. We may also choose to act as our own warrant agent. We will indicate the name and address of any warrant agent in the applicable prospectus supplement relating to a particular series of warrants.

We will describe in the applicable prospectus supplement the terms of the series of warrants, including:

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to 5:00 P.M. eastern time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information and paying the required exercise price by the methods provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate, and in the applicable prospectus supplement, the information that the holder of the warrant will be required to deliver to the warrant agent.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants.

Enforceability of Rights By Holders of Warrants

Any warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank, transfer agent or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action the holder’s right to exercise, and receive the securities purchasable upon exercise of, its warrants in accordance with their terms.

Warrant Agreement Will Not Be Qualified Under Trust Indenture Act

No warrant agreement will be qualified as an indenture, and no warrant agent will be required to qualify as a trustee, under the Trust Indenture Act. Therefore, holders of warrants issued under a warrant agreement will not have the protection of the Trust Indenture Act with respect to their warrants.

Governing Law

Each warrant agreement and any warrants issued under the warrant agreements will be governed by the law identified in the applicable prospectus supplement.

Calculation Agent

Any calculations relating to warrants may be made by a calculation agent, an institution that we appoint as our agent for this purpose. The prospectus supplement for a particular warrant will name the institution that we have appointed to act as the calculation agent for that warrant as of the original issue date for that warrant, if any. We may appoint a different institution to serve as calculation agent from time to time after the original issue date without the consent or notification of the holders. The calculation agent’s determination of any amount of money payable or securities deliverable with respect to a warrant will be final and binding in the absence of manifest error.

DEBT SECURITIES

We may issue debt securities, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. When we offer to sell debt securities, we will describe the specific terms of any debt securities offered from time to time in a supplement to this prospectus, which may supplement or change the terms outlined below. Senior debt securities will be issued under one or more senior indentures, dated as of a date prior to such issuance, between us and a trustee to be named in a prospectus supplement, as amended or supplemented from time to time. Any subordinated debt securities will be issued under one or more subordinated indentures, dated as of a date prior to such issuance, between us and a trustee to be named in a prospectus supplement, as amended or supplemented from time to time. We have filed forms of the senior trust indenture and subordinated indenture as exhibits to the registration statement of which this prospectus is a part. The indentures will be subject to and governed by the Trust Indenture Act of 1939, as amended.

The indentures in the forms initially filed as exhibits to the registration statement of which this prospectus forms a part do not limit the amount of debt securities that we may issue, including senior debt securities, senior subordinated debt securities, subordinated debt securities and junior subordinated debt securities, and do not limit us from issuing any other debt, including secured and unsecured debt. We may issue debt securities up to an aggregate principal amount as we may authorize from time to time. The terms of each series of debt securities will be established by or pursuant to (a) a supplemental indenture, (b) a resolution of our Board of Directors, or (c) an officers’ certificate pursuant to authority granted under a resolution of our Board of Directors. For the complete terms of the debt securities, you should refer to the applicable prospectus supplement and the form of indentures for those particular debt securities. The prospectus supplement will describe the terms of any debt securities being offered, including:

Conversion or Exchange Rights

We will set forth in the prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

UNITS

We may issue units comprised of one or more of the other securities described in this prospectus or in any prospectus supplement in any combination. Each unit will be issued so that the holder of the unit is also the holder, with the rights and obligations of a holder, of each security included in the unit. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date or upon the occurrence of a specified event or occurrence.

The applicable prospectus supplement will describe:

SUBSCRIPTION RIGHTS

We may issue subscription rights to purchase common stock, preferred stock, debt securities, warrants, units and other securities described in this prospectus or any combination thereof. These subscription rights may be issued independently or together with any other security offered by us and may or may not be transferable by the stockholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other investors pursuant to which the underwriters or other investors may be required to purchase any securities remaining unsubscribed for after such offering.

To the extent appropriate, the applicable prospectus supplement will describe the specific terms of the subscription rights to purchase shares of our securities offered thereby, including the following:

Anti-Takeover Effects of Certain Provisions of Delaware Law and Our Charter Documents

The following is a summary of certain provisions of the DGCL, our Amended and Restated Certificate of Incorporation and our Amended and Restated Bylaws. This summary does not purport to be complete and is qualified in its entirety by reference to the DGCL and our Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws.

Effect of Delaware Anti-Takeover Statute. We are subject to Section 203 of the Delaware General Corporation Law, an anti-takeover law. In general, Section 203 prohibits a Delaware corporation from engaging in any business combination (as defined below) with any interested stockholder (as defined below) for a period of three years following the date that the stockholder became an interested stockholder, unless:

Section 203 defines “business combination” to include the following:

In general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation, or who beneficially owns 15% or more of the outstanding voting stock of the corporation at any time within a three-year period immediately prior to the date of determining whether such person is an interested stockholder, and any entity or person affiliated with or controlling or controlled by any of these entities or persons.

Our Charter Documents. Our charter documents include provisions that may have the effect of discouraging, delaying or preventing a change in control or an unsolicited acquisition proposal that a stockholder might consider favorable, including a proposal that might result in the payment of a premium over the market price for the shares held by our stockholders. Certain of these provisions are summarized in the following paragraphs.

Effects of authorized but unissued common stock. One of the effects of the existence of authorized but unissued common stock may be to enable our Board of Directors to make more difficult or to discourage an attempt to obtain control of our Company by means of a merger, tender offer, proxy contest or otherwise, and thereby to protect the continuity of management. If, in the due exercise of its fiduciary obligations, the Board of Directors were to determine that a takeover proposal was not in our best interest, such shares could be issued by the Board of Directors without stockholder approval in one or more transactions that might prevent or render more difficult or costly the completion of the takeover transaction by diluting the voting or other rights of the proposed acquirer or insurgent stockholder group, by putting a substantial voting block in institutional or other hands that might undertake to support the position of the incumbent Board of Directors, by effecting an acquisition that might complicate or preclude the takeover, or otherwise.

Cumulative Voting. Our Amended and Restated Certificate of Incorporation does not provide for cumulative voting in the election of directors, which would allow holders of less than a majority of the stock to elect some directors.

Vacancies. Our Amended and Restated Certificate of Incorporation provides that all vacancies may be filled by the affirmative vote of a majority of directors then in office, even if less than a quorum.

Special Meeting of Stockholders and Stockholder Action by Written Consent. A special meeting of stockholders may only be called by our president, Board of Directors, or such officers or other persons as our board may designate at any time and for any purpose or purposes as shall be stated in the notice of the meeting.

PLAN OF DISTRIBUTION

We may sell the securities being offered pursuant to this prospectus to or through underwriters, through dealers, through agents, or directly to one or more purchasers or through a combination of these methods. The applicable prospectus supplement will describe the terms of the offering of the securities, including:

We may distribute the securities from time to time in one or more transactions at:

Only underwriters named in the prospectus supplement are underwriters of the securities offered by the prospectus supplement.

If underwriters are used in an offering, we will execute an underwriting agreement with such underwriters and will specify the name of each underwriter and the terms of the transaction (including any underwriting discounts and other terms constituting compensation of the underwriters and any dealers) in a prospectus supplement. The securities may be offered to the public either through underwriting syndicates represented by managing underwriters or directly by one or more investment banking firms or others, as designated. If an underwriting syndicate is used, the managing underwriter(s) will be specified on the cover of the prospectus supplement. If underwriters are used in the sale, the offered securities will be acquired by the underwriters for their own accounts and may be resold from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time. Unless otherwise set forth in the prospectus supplement, the obligations of the underwriters to purchase the offered securities will be subject to conditions precedent, and the underwriters will be obligated to purchase all of the offered securities, if any are purchased.

We may grant to the underwriters options to purchase additional securities to cover over-allotments, if any, at the public offering price, with additional underwriting commissions or discounts, as may be set forth in a related prospectus supplement. The terms of any over-allotment option will be set forth in the prospectus supplement for those securities.

If we use one or more dealers in the sale of the securities being offered pursuant to this prospectus or any prospectus supplement, we will sell the securities to the dealer, as principal. The dealers may then resell the securities to the public at varying prices to be determined by each dealer at the time of resale. The names of the dealers and the terms of the transaction will be specified in a prospectus supplement.

We may sell the securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement.

We may authorize agents or underwriters to solicit offers by institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

In connection with the sale of the securities, underwriters, dealers or agents may receive compensation from us or from purchasers of the securities for whom they act as agents, in the form of discounts, concessions or commissions. Underwriters may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agents. Underwriters, dealers and agents that participate in the distribution of the securities, and any institutional investors or others that purchase securities directly for the purpose of resale or distribution, may be deemed to be underwriters, and any discounts or commissions received by them from us and any profit on the resale of the securities by them may be deemed to be underwriting discounts and commissions under the Securities Act of 1933 (the “Securities Act”).

We may provide agents, underwriters and other purchasers with indemnification against particular civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents, underwriters or other purchasers may make with respect to such liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

To facilitate the public offering of a series of securities, persons participating in the offering may engage in transactions that stabilize, maintain, or otherwise affect the market price of the securities. This may include over-allotments or short sales of the securities, which involves the sale by persons participating in the offering of more securities than have been sold to them by us. In addition, those persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to underwriters or dealers participating in any such offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. Such transactions, if commenced, may be discontinued at any time. We make no representation or prediction as to the direction or magnitude of any effect that the transactions described above, if implemented, may have on the price of our securities.

Unless otherwise specified in the applicable prospectus supplement, any common stock sold pursuant to a prospectus supplement will be eligible for listing on the Nasdaq Global Market, subject to official notice of issuance. Any underwriters to whom securities are sold by us for public offering and sale may make a market in the securities, but such underwriters will not be obligated to do so and may discontinue any market making at any time without notice.

In order to comply with the securities laws of some states, if applicable, the securities offered pursuant to this prospectus will be sold in those states only through registered or licensed brokers or dealers. In addition, in some states securities may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and complied with.

LIMITATIONS ON LIABILITY AND INDEMNIFICATION OF OFFICERS AND DIRECTORS

The DGCL provides that corporations may include a provision in their certificate of incorporation relieving directors of monetary liability for breach of their fiduciary duty as directors, provided that such provision shall not eliminate or limit the liability of a director (i) for any breach of the director’s duty of loyalty to the corporation or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) for unlawful payment of a dividend or unlawful stock purchase or redemption, or (iv) for any transaction from which the director derived an improper personal benefit. Our certificate of incorporation provides that directors are not liable to us or our stockholders for monetary damages for breach of their fiduciary duty as directors to the fullest extent permitted by Delaware law. In addition to the foregoing, our certificate of incorporation provides that we may indemnify directors and officers to the fullest extent permitted by law.

The above provisions in our Amended and Restated Certificate of Incorporation may have the effect of reducing the likelihood of derivative litigation against directors and may discourage or deter stockholders or management from bringing a lawsuit against directors for breach of their fiduciary duty, even though such an action, if successful, might otherwise have benefited us and our stockholders. However, we believe that the foregoing provisions are necessary to attract and retain qualified persons as directors.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to our directors, officers and controlling persons pursuant to the foregoing provisions, or otherwise, we have been advised that in the opinion of the SEC, such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable.

LEGAL MATTERS

Certain legal matters with respect to the validity of certain of the offered securities will be passed upon for us by Croke Fairchild Morgan & Beres LLC, Chicago, Illinois. If counsel for any underwriters passes on legal matters in connection with an offering of the shares of the securities described in this prospectus, we will name that counsel in the prospectus supplement relating to that offering.

EXPERTS

The financial statements of the Company as of and for the periods ended December 31, 2018 and 2017, included in our Annual Report on Form 10-K filed on March 25, 2019, were audited by KMJ Corbin & Company LLP, an independent registered public accounting firm, as stated in their report which is incorporated herein by reference in reliance on the report of such firm given upon their authority as experts in accounting and auditing.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

This prospectus “incorporates by reference” information that we have filed with the SEC under the Securities Exchange Act of 1934 (the “Exchange Act”). This means that we are disclosing important information to you by referring you to those documents. Information contained in any document subsequently filed with the SEC, to the extent it modifies information in this prospectus or in any document incorporated by reference in this prospectus, will automatically update and supersede the information originally included in this prospectus or any document incorporated by reference in this prospectus.

We incorporate by reference the following documents that we previously filed with the SEC pursuant to the Securities Act or the Exchange Act:

(a) Annual Report on Form 10-K for the fiscal year ended December 31, 2018, as filed with the SEC on March 25, 2019;

(b) Quarterly Reports on Form 10-Q for the quarter ended March 31, 2019 as filed with the SEC on May 7, 2019, for the quarter ended June 30, 2019, as filed with the SEC on August 6, 2019, and for the quarter ended September 30, 2019, as filed with the SEC on November 14, 2019

(c) Current Reports on Form 8-K, filed with the Commission on January 24, 2019 (with respect to Item 1.01), February 11, 2019 (with respect to Item 1.01), February 19, 2019 (with respect to Item 1.01), March 25, 2019 (with respect to Items 2.02 and 9.01), May 7, 2019 (with respect to Items 2.02 and 9.01), June 12, 2019 (with respect to Item 5.07), June 13, 2019 (with respect to Items 8.01 and 9.01), July 12, 2019 (with respect to Items 8.01 and 9.01), August 1, 2019 (with respect to Items 8.01 and 9.01), August 6, 2019 (with respect to Items 2.02 and 9.01), August 19, 2019 (with respect to Items 8.01 and 9.01), October 22, 2019 (with respect to Items 8.01 and 9.01), and November 14, 2019 (with respect to Items 2.02, 8.01, and 9.01);

(d) The description of the company’s securities contained in the Company’s Registration Statement on Form 8-A filed with the SEC on November 8, 2018, pursuant to Section 12(b) of the Exchange Act, including any amendments or reports filed for the purpose of updating such descriptions; and

(e) All other reports filed pursuant to Section 13(a) or 15(d) of the Exchange Act, since the end of the fiscal year covered by the Annual Report referred to in (a) above.

Information in this prospectus supersedes related information in the documents listed above, and information in subsequently filed documents supersedes related information in both this prospectus and the incorporated documents.

All documents filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, after the date of this registration statement and prior to the filing of a post-effective amendment which indicates that all securities offered hereby have been sold or which deregisters all securities then remaining unsold shall be deemed to be incorporated by reference into this registration statement and to be a part hereof from the date of filing of such documents.

Each statement made in this prospectus or any prospectus supplement concerning a document filed as an exhibit to the registration statement is qualified in its entirety by reference to that exhibit for a complete description of its provisions. Any document, and any statement contained in a document, incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein, or in any other subsequently filed document that also is incorporated or deemed to be incorporated by reference herein, modifies or supersedes such document or statement. Any such document or statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

The documents incorporated by reference in this prospectus may be obtained from us without charge and will be provided to each person, including any beneficial owner, to whom a prospectus is delivered. You may obtain a copy of the documents at no cost by submitting an oral or written request to 21925 W. Field Parkway, Suite 235, Deer Park, Illinois, 60010, or through our telephone number at (847) 787-7361. Further information can be obtained through our website address, www.etonpharma.com. Such additional information contained in our web site is not a part of this prospectus.

WHERE YOU CAN FIND ADDITIONAL INFORMATION ABOUT US

This prospectus is part of a registration statement on Form S-3 that we filed with the SEC registering the securities that may be offered and sold hereunder. The registration statement, including exhibits thereto, contains additional relevant information about us and the securities that may be offered and sold hereunder, as permitted by the rules and regulations of the SEC, we have not included in this prospectus. A copy of the registration statement can be obtained at the address set forth below or at the SEC’s website as noted below. You should read the registration statement, including any applicable prospectus supplement, for further information about us and the securities.

We file annual, quarterly and special reports, proxy statements and other information with the SEC. You may read and copy any document we file with the SEC at the SEC’s Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330. The SEC also maintains a website that contains reports, proxy statements, information statements and other information about issuers, like Eton, that file electronically with the SEC. The address of that website is www.sec.gov. The website, and, except as expressly incorporated herein, the information contained therein, is not a part of this prospectus. You may also obtain copies of the documents at prescribed rates by writing to the SEC’s Public Reference Section at 100 F Street, N.E., Washington, D.C. 20549.

2,800,000 Shares

Common Stock

PROSPECTUS SUPPLEMENT

Sole Book-Running Manager

National Securities Corporation

October 14, 2020