Company: SNY
Filing Date: 2025-10-27
Form Type: 424B5
Source: 0001193125-25-250786
Chunk: 11

Company: Sanofi
Filing Date: 2025-10-27
Form: 424B5
Chunk 11
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20   fixed rate notes will bear interest from   , 2025 at a fixed rate of   % per annum. |

| The 20   fixed rate notes will bear interest from   , 2025 at a fixed rate of   % per annum. |

| Interest Payment Dates | Interest on the fixed rate notes will be paid semi-annually in arrears on   and   of each year, commencing on   , 2026. |

| Regular Record Dates | Close of business on   and |

S-8

| Day Count Convention | Interest on the fixed rate notes will be calculated on the basis of a 360-day year consisting of twelve 30-day months. |

| If any payment is due on the fixed rate notes on a day that is not a business day (as defined in “Description of the Notes” in this prospectus supplement), we will make the payment on the day that is the                                           
 next business day. Payments postponed to the next business day in this situation will be treated as if they were made on the original due date. Postponements of this kind will not result in a default, and no interest will accrue on the postponed 
 amount from the original due date to the next day that is a business day.                                                                                                                                                                             |

| Optional Redemption | Prior to   , 20   , in the case of the 20   Fixed Rate Notes and   , 20   , in the case of the 20   Fixed Rate Notes (each a “Par                                                                                                                  
 Call Date”) the Issuer may redeem the relevant series of Fixed Rate Notes at its option, in whole or in part, at any time and from time to time, at a redemption price (expressed as a percentage of principal amount and rounded to three decimal 
 places) equal to the greater of:                                                                                                                                                                                                                   |

(1) (a) the sum of the present values of the Remaining Scheduled Payments of principal and interest thereon discounted to the redemption date (assuming the relevant Notes matured on the Par Call Date) on a semi-annual basis (assuming a 360-dayyear consisting of twelve