Company: SNY
Filing Date: 2025-10-29
Form Type: 424B5
Source: 0001193125-25-255563
Chunk: 85

Company: Sanofi
Filing Date: 2025-10-29
Form: 424B5
Chunk 85
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 with those actions and enforce in France judgments obtained in such actions in U.S. courts against us or them. In addition, we cannot assure you that civil liabilities predicated upon the federal securities laws of the United States will be enforceable in France. See “Enforceability of Certain Civil Liabilities.” 9

USE OF PROCEEDS

Unless otherwise indicated in an accompanying prospectus supplement, we will use the net proceeds from the sale of the debt securities for
general financing and corporate purposes.

10

DESCRIPTION OF DEBT SECURITIES WE MAY OFFER General We may issue debt securities using this prospectus. The debt securities that we may issue will be governed by a contract between us and Deutsche Bank Trust Company Americas, as trustee, called an indenture. The trustee under the indenture has two main roles:

| • |     | first, it can enforce your rights against us if we default. There are some limitations on the extent to which the                                    
 trustee acts on your behalf, described under “— Default and Related Matters — Events of Default — Remedies If an Event of Default Occurs” below; and |

| • |     | second, the trustee performs administrative duties for us, such as sending you interest payments, transferring                             
 your debt securities to a new buyer if you sell your debt securities (and they are not held in a clearing system) and sending you notices. |

The indenture and its associated documents contain the full legal text governing the matters described in this section. The indenture and the debt securities are governed by New York law. A form of the indenture is an exhibit to our registration statement. See “Where You Can Find More Information” for information on how to obtain a copy. We may issue either senior or subordinated debt securities using this prospectus. Neither the senior debt securities nor the subordinated debt securities will be secured by any of our property or assets. Thus, by owning a debt security, you are an unsecured creditor of ours. The senior debt securities will be issued under the indenture described below. If we issue subordinated debt securities, they will be issued under a supplemental subordinated debt indenture, which will describe the terms thereof, including provisions relating to subordination. If we issue subordinated debt securities, they will be subordinated in right of payment to all of our “senior indebtedness,” as defined in the supplemental subordinated debt indenture. When we refer to “debt securities” in this prospectus, and except as otherwise specified, we mean the