Peptides for Weight Loss
Last reviewed
Three peptide drugs are FDA-approved for weight management. Others marketed for weight loss are still in trials or have no approval at all. Here's which is which, with a source for each.
The short version
- FDA-approved for chronic weight management: Wegovy (semaglutide), Zepbound (tirzepatide) and Saxenda (liraglutide). All are prescription injections.
- In trials, not approved: retatrutide. Its maker says it can't legally be sold for human use.
- Everything else sold online "for weight loss" isn't FDA-approved for that use.
Weight-loss peptides by FDA status
| Peptide | Brand | Status for weight loss |
|---|---|---|
| Semaglutide | Wegovy | FDA-approved June 2021, for chronic weight management. The same ingredient is sold as Ozempic and Rybelsus for type 2 diabetes. |
| Tirzepatide | Zepbound | FDA-approved November 2023, for chronic weight management. The same ingredient is sold as Mounjaro for type 2 diabetes. |
| Liraglutide | Saxenda | FDA-approved December 2014, for chronic weight management. |
| Retatrutide | None | Investigational Phase 3 results reported in 2026; Eli Lilly plans to submit it to the FDA in early 2027. Not approved. |
| Tesamorelin | Egrifta | Different use Approved only to reduce excess abdominal fat in adults with HIV-associated lipodystrophy, not for general weight loss. |
| MOTS-c | None | Not approved The original 2015 research on it was in mice. Its compounding status is awaiting the FDA. |
Who the approved drugs are for
Wegovy, Zepbound and Saxenda are approved for adults with obesity (a BMI of 30 or higher) or with overweight (a BMI of 27 or higher) plus at least one weight-related condition. They're meant to be used along with a reduced-calorie diet and more physical activity, and all require a prescription.
How they work
Semaglutide and liraglutide mimic GLP-1, a gut hormone. The FDA says Wegovy works on areas of the brain that regulate appetite and food intake. Tirzepatide acts on two gut hormones, GLP-1 and GIP. Retatrutide, still in trials, targets three: GIP, GLP-1 and glucagon.
Side effects and warnings
The FDA lists common side effects for Wegovy and Zepbound that include nausea, diarrhea, vomiting, constipation, abdominal pain and fatigue. Wegovy carries a boxed warning about a possible risk of thyroid C-cell tumors, and tirzepatide caused thyroid C-cell tumors in rats. People with a personal or family history of medullary thyroid carcinoma, or with Multiple Endocrine Neoplasia syndrome type 2, shouldn't use Wegovy. The full list is in each drug's prescribing information, and a prescriber can explain what applies to you. More on this in Are peptides safe?
Compounded and online versions
Semaglutide and tirzepatide are also sold as compounded or unapproved products. The FDA has warned that unapproved GLP-1 drugs don't go through its review for safety, effectiveness and quality, that it has seen compounded semaglutide and tirzepatide with false label information, and that it has received reports of dosing errors with compounded semaglutide, some needing hospital care. In February 2026 the FDA also announced restrictions on the ingredients used in mass-marketed compounded versions.
One tell: brand-name Ozempic and Zepbound come as a ready-to-inject liquid, according to their prescribing information. A vial of powder that needs water added isn't one of the FDA-approved products. If a pharmacy compounded yours, follow its label and your prescriber exactly; our tirzepatide and semaglutide calculators can double-check the arithmetic.
The bottom line
If you're considering a peptide for weight loss, the FDA-approved options are prescription drugs with known benefits, side effects and warnings. A licensed clinician can tell you whether one fits your situation. We don't recommend products or amounts.
Frequently asked questions
Are any peptides FDA-approved for weight loss?
Yes: Wegovy (semaglutide), Zepbound (tirzepatide) and Saxenda (liraglutide), all prescription injections for adults who meet specific BMI criteria.
Is retatrutide FDA-approved?
No. It's investigational. Eli Lilly plans to submit it to the FDA in the first quarter of 2027 and states it can't legally be sold or marketed for human use.
Can you get weight-loss peptides without a prescription?
The FDA-approved ones require a prescription. The FDA has warned about unapproved GLP-1 products, including compounded semaglutide and tirzepatide with false label information.
Is semaglutide a peptide?
Yes. Semaglutide is a modified version of GLP-1, a natural peptide hormone. See What are peptides?
Sources
- FDA: FDA approves new drug treatment for chronic weight management, first since 2014 (Wegovy, June 4, 2021)
- FDA: FDA approves new medication for chronic weight management (Zepbound, November 8, 2023)
- Pharmacy Times: FDA approves Saxenda for long-term weight management (2014)
- Eli Lilly: Retatrutide phase 3 results (July 23, 2026)
- FDA: Concerns with unapproved GLP-1 drugs used for weight loss
- AJMC: 5 things to know about the FDA's peptide reversal (2026)
- Egrifta SV prescribing information (Drugs.com)
- Lee et al., MOTS-c, Cell Metabolism (2015)