Overview
Semaglutide is contraindicated in MTC, MEN 2, pregnancy, breastfeeding. Boxed warning: thyroid C-cell tumors (rodent studies, human relevance unknown).
Questions readers ask
Who should not take semaglutide?
Semaglutide is contraindicated in people with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), and during pregnancy and breastfeeding. A licensed clinician reviews your history before prescribing.
What does the semaglutide boxed warning mean for humans?
The boxed warning, FDA’s most stringent label warning, concerns thyroid C-cell tumors seen in rodent studies. Whether this risk applies to humans is unknown, which is why people with an MTC or MEN 2 history are excluded from treatment.
Do the same contraindications apply to compounded semaglutide?
Compounded semaglutide contains the same active ingredient, so the same safety screening applies. Compounded drugs are not FDA-approved, and eligibility is decided by a licensed clinician; FDA has also warned against salt forms such as semaglutide sodium and semaglutide acetate.
Primary sources
- FDA: Concerns with unapproved GLP-1 drugs used for weight loss (current as of October 1, 2026)
- FDA: Policies for compounders as GLP-1 supply stabilizes (updated April 1, 2026)
- FDA: Compounding and the FDA — questions and answers
- FDA: Registered outsourcing facilities (503B)
- Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021
- Wegovy (semaglutide) prescribing information, Novo Nordisk