SEC Form 424B3 filed by Jupiter Neurosciences Inc.

Filed pursuant to Rule 424(b)(3)

Registration No. 333-291832

Prospectus Supplement No. 5

(To Prospectus dated December 11, 2025)

Jupiter Neurosciences, Inc.

This prospectus supplement updates, amends and supplements the prospectus dated December 11, 2025 (the “Prospectus”), which forms a part of our Registration Statement on Form S-1 (Registration No. 333-291832) and is being filed to update, amend and supplement the information included in the Prospectus with information contained in our Current Report on Form 8-K, which was filed with the Securities and Exchange Commission (the “SEC”) on June 5, 2026 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement. Capitalized terms used in this prospectus supplement and not otherwise defined herein have the meanings specified in the Prospectus.

This prospectus supplement is not complete without the Prospectus. This prospectus supplement should be read in conjunction with the Prospectus, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extent that the information in this prospectus supplement updates or supersedes the information contained in the Prospectus. Please keep this prospectus supplement with your Prospectus for future reference.

Shares of our common stock, par value $0.0001 per share (our “Common Stock”), are listed on The Nasdaq Stock Market, LLC under the symbol “JUNS.” On June 4, 2026, the closing price of our Common Stock was $ 0.2550 per share.

Investing in our securities involves risks that are described in the “Risk Factors” section of the Prospectus.

Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued under the Prospectus or this prospectus supplement or determined if the Prospectus or this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is June 5, 2026.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

June 2, 2026

Date of Report (Date of earliest event reported)

JUPITER NEUROSCIENCES, INC.

(Exact name of registrant as specified in its charter)

(561) 406-6154

Registrant’s telephone number, including area code

Check the appropriate box below if the Form 8-K is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging Growth Company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(e) Compensatory Arrangements of Certain Officers

The following sets forth certain compensatory arrangements entered into, adopted or modified by Jupiter Neurosciences, Inc. (the “Company”) during the period covered by this Current Report.

Alison Silva

On June 5, 2026, the Company entered into amendment No. 3 (the “Amendment”) to the employment agreement with Alison Silva, dated September 1, 2021, as amended. The Amendment appoints Ms. Silva as the Company’s Chief Operating Officer and President and increases Ms. Silva’s base salary to $340,200 from $315,000. In connection with the Amendment, on June 2, 2026, the board of directors of the Company (the “Board”), based on the recommendation of the compensation committee of the Board (the “Compensation Committee”), approved a one-time grant of options to purchase up to 600,000 shares of the Company’s common stock under the Jupiter Neurosciences, Inc. 2025 Equity Incentive Plan (the “Plan”) to Ms. Silva with an exercise price equal to the closing price of the Company’s common stock on the Nasdaq Capital Market on the date of grant to recognize her contributions to the Company. Such option grant vests over three years commencing from September 2, 2026 in equal quarterly installments, subject to the recipient’s continued service with the Company through each applicable vesting date.

The foregoing summary of the Amendment does not purport to be complete and is subject to, and qualified in its entirety, by the full text of the Amendment, a copy of which is attached to this Current Report as Exhibit 10.1.

Director Compensation

On June 2, 2026, the Compensation Committee approved a grant of stock options to each of the Company’s independent non-employee directors to purchase up to 100,000 shares of the Company’s common stock under the Plan, with an exercise price per share equal to the closing price of the Company’s common stock on the Nasdaq Capital Market on the date of grant. Such option grants vest over three years commencing from September 2, 2026 in equal quarterly installments, subject to the recipient’s continued service with the Company through each applicable vesting date.

Discretionary Bonus Options in Lieu of Cash and Long-Term Incentive Compensation

On June 2, 2026, the Board, based on the recommendation of the Compensation Committee, approved discretionary bonuses to the following executives in the form of stock options under the Plan in lieu of cash:

In addition, the Board, based on the recommendation of the Compensation Committee, approved a one-time grant of options to purchase up to 200,000 shares of the Company’s common stock under the Plan to Mr. Elmasri with an exercise price equal to the closing price of the Company’s common stock on the Nasdaq Capital Market on the date of grant to recognize his contributions to the Company. Each such grant vests over three years commencing from September 2, 2026 in equal quarterly installments, subject to the recipient’s continued service with the Company through each applicable vesting date.

Item 9.01. Financial Statements and Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit 10.1

Amendment No. 3 to Executive Employment Agreement

Dated as of June 5, 2026

This Amendment No. 3 to Executive Employment Agreement (this “Amendment”) dated as of the date first set forth above (the “Amendment Date”) is entered into by and between Jupiter Neurosciences, Inc., a Delaware corporation (the “Company”), and Alison Silva (the “Executive”). The Company and Executive may collectively be referred to as the “Parties” and each individually as a “Party”.

WHEREAS, the Parties are the parties to that certain Executive Employment Agreement, dated as of September 1, 2021 (the “Original Agreement”), as amended by that certain Amendment to Executive Employment Agreement dated as of September 29, 2021 (“Amendment No. 1”), and that certain Amendment to Executive Employment Agreement dated as of December 18, 2023 (“Amendment No. 2,” and together with the Original Agreement and Amendment No. 1, the “Agreement”), and now desire to further amend the Agreement as set forth herein and pursuant to Section 14 of the Original Agreement the Parties may amend the Agreement in writing;

NOW, THEREFORE, in consideration of the promises and of the mutual covenants and agreements hereinafter set forth, and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties hereby agree as follows:

[Signatures appear on following page]

IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be executed as of the Amendment Date.