Reporting Side Effects

Patient health and ensuring the safety of our products is our top priority. In order for us to monitor and assess the ongoing safety of our treatments, we encourage patients and their health care providers to report suspected side effects.

How to report

Side effects (also called "adverse effects" or "adverse events") refer to the unintended or undesirable events subsequent to use of a medical treatment. They can sometimes be minor, but they can also involve serious health issues.

If you believe you have experienced a side effect from one of our treatments, please take the following actions:

Contact your doctor

If you believe you're experiencing side effects – or any other medical problems – the first thing you should do is contact your doctor or other health care providers so they can determine if any action needs to be taken.

U.S. residents: report to the FDA

If you're in the United States, you are encouraged to report negative side effects of prescription drugs directly to the U.S. Food and Drug Administration (FDA) via its MedWatch program:

Contact Sanofi Genzyme

If you are a patient in the United States taking a Sanofi Genzyme product and you are experiencing side effects, please inform us of your experience. (If you are outside the U.S., speak with your health care provider about local reporting requirements.)

To report side effects, call Sanofi Genzyme Medical Information at 800-745-4447, option 2. A Sanofi Genzyme representative will take your preliminary information. After reviewing this information, we may follow up with you or (with your permission) your physician for additional details.

Before contacting us, please have the following information ready:

  • Patient name, age, gender, and weight
  • Patient phone number
  • Physician name and phone number
  • Sanofi Genzyme product taken and dosage
  • Brief description of side effects

Contact Medical Information

For U.S. and Canada call

800-745-4447 (toll-free) or 617-768-9000

or use our contact form for other regions. 


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