Company: SNY
Filing Date: 2025-10-29
Form Type: 424B5
Source: 0001193125-25-255563
Chunk: 75

Company: Sanofi
Filing Date: 2025-10-29
Form: 424B5
Chunk 75
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 the Group, may have the
same unfavorable effect and investors may lose all or part of their investment.

Forward-looking statements speak only as of the date they
are made. Other than required by law, we do not undertake any obligation to update them in light of new information or future developments.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational reporting requirements of the Securities Exchange Act of 1934 (the “Exchange Act”) applicable
to foreign private issuers and file annual and other information with the SEC. You may read and copy any document that we file with the SEC at the SEC’s public reference room at 100 F Street, N.E., Room 1580, Washington, D.C. 20549. In
addition, our SEC filings are available to the public at the SEC’s website at http://www.sec.gov. For further information, please call the SEC at
1-800-SEC-0330 or log on to http://www.sec.gov.

Our website address is http://www.sanofi.com. The information on our website, however, is not, and should not be deemed to be, a part of this
prospectus.

Our shares are listed on Euronext Paris and the NASDAQ Global Select Market, the latter in the form of American Depository
Shares (“ADSs”) and you can consult reports and other information about us that are filed pursuant to the rules of Euronext Paris and the NASDAQ Global Select Market at these securities exchanges or inter-dealer quotation systems.

2

INCORPORATION BY REFERENCE We have filed with the SEC a registration statement on Form F-3relating to the debt securities covered by this prospectus. This prospectus is a part of that registration statement and does not contain all of the information in that registration statement. Whenever a reference is made in this prospectus to a contract or other document of Sanofi, the reference is only a summary. You should refer to the exhibits that are a part of the registration statement for a copy of the contract or other document. You may review a copy of the registration statement at the SEC’s public reference room in Washington, D.C., as well as through the SEC’s Internet site at http://www.sec.gov. The SEC allows us to incorporate by reference the information we file with them, which means that:

| • |     | incorporated documents are considered part of this prospectus; |

| • |     | we can disclose important information to you by referring to those documents