Company: SNY
Filing Date: 2025-10-27
Form Type: 424B5
Source: 0001193125-25-250786
Chunk: 49

Company: Sanofi
Filing Date: 2025-10-27
Form: 424B5
Chunk 49
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, each of the
20 floating rate notes, the 20 floating rate notes, 20 fixed rate notes, the 20 fixed rate notes and the 20 fixed rate notes will be considered a
separate series. See “Description of Debt Securities We May Offer — Special Situations — Modification and Waiver” and “Description of Debt Securities We May Offer — Default and Related Matters — Events of
Default” in the attached prospectus.

Trustee, Security Registrar, Paying Agent and Calculation Agent

The trustee, security registrar, paying agent and calculation agent under our Indenture is Deutsche Bank Trust Company Americas. See “Description of Debt
Securities We May Offer — Regarding the Trustee” and “Description of Debt Securities We May Offer — Default and Related Matters” in the attached prospectus for a description of the trustee’s procedures and
remedies available in the event of default.

Sanofi U.S. Services Inc. and Authorized Agent Change of Address

The address of Sanofi U.S. Services Inc. and therefore of the Authorized Agent, to be used, from now on is: 100 Morris Street, Morristown, New Jersey, 07960,
U.S.A.

S-37

TAXATION

The following description of tax considerations supersedes in its entirety the description under the heading “Taxation of Debt Securities” in the attached prospectus.

French Taxation

The following generally summarizes the material French tax consequences of purchasing, owning and disposing of the notes described in this
prospectus supplement. The statements related to French tax laws set forth below are based on the laws in force as of the date hereof, and are subject to any changes in applicable laws and tax treaties after such date.

This discussion applies to notes that are in the form of “obligations” under French law for purposes of taxation which are
held by holders that (i) are not shareholders of the Issuer, (ii) are not related parties to the relevant issuer of the debt securities within the meaning of Article 39,12 of the French General Tax Code and (iii) do not hold debt
securities in connection with a business or profession conducted in France or a permanent establishment or a fixed base in France.

This
discussion is intended only as a descriptive summary and does not purport to be a complete analysis or listing of all potential effects of the purchase, ownership or disposition of the notes described in this prospectus.

The following summary does not address the treatment of the notes that are