Peptides for weight loss: which are approved, and which are not?

Which peptides are FDA-approved for weight loss?

Four peptide drugs carry an FDA-approved weight indication on DiscoverMedica’s list: semaglutide (Wegovy), tirzepatide (Zepbound), liraglutide (Saxenda) and setmelanotide (Imcivree). The first three are GLP-1 based medicines for adults with obesity, or overweight with a weight-related condition; setmelanotide is limited to specific rare causes of obesity. Wegovy label

• Semaglutide (Wegovy): approved for chronic weight management and to reduce the risk of major heart events in adults with heart disease and obesity or overweight. Wegovy label
• Tirzepatide (Zepbound): approved for chronic weight management and for moderate to severe obstructive sleep apnea in adults with obesity. Zepbound label
• Liraglutide (Saxenda): approved for chronic weight management in adults and some adolescents. Saxenda label
• Setmelanotide (Imcivree): approved to reduce excess body weight in people with Bardet-Biedl syndrome, acquired hypothalamic obesity, or POMC, PCSK1 or LEPR deficiency confirmed by genetic testing. Imcivree label

How much weight did people lose in the trials?

In their main trials, people taking the approved GLP-1 peptides lost more weight on average than people taking placebo, alongside lifestyle counseling. These are trial averages: individual results vary widely, and the trials enrolled adults with obesity or overweight plus a weight-related condition. STEP 1

STEP 1 enrolled 1,961 adults without diabetes; nausea and diarrhea were the most common side effects. STEP 1

SURMOUNT-1 enrolled 2,539 adults without diabetes; the most common side effects were gastrointestinal and mostly mild to moderate. SURMOUNT-1

SCALE enrolled 3,731 adults without type 2 diabetes; mild or moderate nausea and diarrhea were the most frequent side effects. SCALE Obesity and Prediabetes

Which weight-loss peptides are not approved?

Retatrutide, cagrilintide, survodutide, mazdutide and AOD-9604 are not FDA-approved in the US. FDA says it has warned companies that illegally sold unapproved drugs containing retatrutide, survodutide or mazdutide, falsely labeled “for research purposes” or “not for human consumption.” FDA

• Retatrutide: in a 48-week phase 2 trial, average weight loss reached 24.2% in the highest-dose group, against 2.1% with placebo. It remains investigational and is not FDA-approved. NEJM 2023
• Cagrilintide and survodutide: studied in human trials, without an FDA-reviewed label. Each has its own status page on DiscoverMedica.
• Mazdutide: approved in China in June 2025 for chronic weight management in adults, but not approved in the US. Shanghai government
• AOD-9604: human studies did not establish it as an approved weight-loss treatment, and it has no FDA approval.

Is every “weight-loss peptide” actually a peptide?

No. Tesofensine is often listed with weight-loss peptides online, but its chemical structure is a small bicyclic amine, not a chain of amino acids. A peptide is a short chain of amino acids; under FDA regulations, a chain of more than 40 amino acids is a protein. PubChem

A protein is, under FDA regulations, any alpha amino acid polymer with a specific, defined sequence that is greater than 40 amino acids in size. 21 CFR 600.3

What about compounded semaglutide and tirzepatide?

Compounded versions are not FDA-approved. With the semaglutide and tirzepatide shortages resolved, FDA says pharmacies should not make copies of the approved drugs, and compounding should be limited to a documented need for an identified patient. The compounded GLP-1 guide covers the details. FDA

Why are research-label weight-loss peptides risky?

Because nothing about them is verified. FDA warns that unapproved GLP-1 products sold online may be counterfeit, or may contain the wrong or harmful ingredients, and that these products have been marketed to consumers despite “research” labels. FDA

FDA judges a product by how it is marketed, not by its disclaimer. Its warning letters cite sellers whose websites promoted human use of products labeled “for research use only.” FDA warning letter

What should you ask a clinician about weight-loss medicines?

Bring your health history, current medicines and goals, and ask questions that compare the approved options for you specifically.

• Which FDA-approved weight medicines fit my health history, and which would you not use for me?
• What side effects should I expect, and which ones mean I should call you?
• What happens if I stop the medicine?
• Will my insurance cover a brand-name drug, and what is the cash price if it does not?
• If you suggest a compounded product, why will an approved drug not meet my needs?

Peptides for weight loss: questions, answered

Sources

1. DailyMed: Wegovy (semaglutide) prescribing information, revised June 2026
2. DailyMed: Zepbound prescribing information
3. DailyMed: Saxenda (liraglutide) prescribing information
4. DailyMed: Imcivree (setmelanotide) prescribing information
5. STEP 1: Once-weekly semaglutide in adults with overweight or obesity (NEJM 2021)
6. SURMOUNT-1: Tirzepatide once weekly for the treatment of obesity (NEJM 2022)
7. SCALE Obesity and Prediabetes: liraglutide in weight management (NEJM 2015)
8. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial (NEJM 2023)
9. Shanghai government: China approves mazdutide for chronic weight management (Jul 2025)
10. FDA: Concerns with unapproved GLP-1 drugs used for weight loss
11. FDA: FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize
12. FDA warning letter: Peptide Partners (Aug 24, 2026)
13. PubChem: Tesofensine (CID 11370864)
14. 21 CFR 600.3: Biological products, definitions (Cornell LII)

Last reviewed October 7, 2026. Every source above was checked on or before that date. Educational information only, not medical advice; it does not replace a conversation with a licensed clinician. DiscoverMedica does not employ clinicians.