Peptide dossier, updated Nov 1, 2026
Retatrutide
Eli Lilly’s investigational once-weekly injection that targets three hormone receptors: GIP, GLP-1 and glucagon (LY3437943). It is not approved anywhere. Lilly says it plans to file for FDA approval in the first quarter of 2027. FDA says it cannot be used in compounding. It is also sold online as a “research” product. This page lays out what each source actually says.
See all 12 verified records for Retatrutide on the Records page
In plain terms
Approved for: Nothing. Retatrutide is not approved for any use by FDA, and FDA says it has not been found safe and effective for any condition.
What it is: A weekly injection that copies three gut and pancreas hormone signals involved in appetite, blood sugar and energy use. Semaglutide and tirzepatide, which are approved, act on one and two of those signals.
What it is said to do, and by whom:
- Eli Lilly, the developer: in its phase 3 trials, adults with obesity and type 2 diabetes lost an average of 20.8% of body weight at 80 weeks on the 12 mg dose, and adults with severe obesity and heart disease lost up to 22.6% (company press release, July 2026).
- Sellers: FDA says some firms falsely label drugs containing retatrutide and other GLP-1s “for research purposes” or “not for human consumption.”
- FDA: says it has not found it safe and effective and that compounded versions are unapproved new drugs.
How strong the evidence is: Early and mostly from the sponsor. Phase 2 results are peer reviewed. For phase 3 we found one peer-reviewed paper (TRIUMPH-2, Lancet, Oct 2026); the other headline figures come from company press releases.
Human studies
ClinicalTrials.gov returns 33 studies for retatrutide as of Nov 1, 2026. All the phase 3 trials we checked are sponsored by Eli Lilly. Registry entries are written by sponsors and are not reviewed for scientific merit.
| Study | What it tests | Status (completion) |
|---|---|---|
| NCT05929066 | Retatrutide in adults with obesity or overweight (TRIUMPH-1 per Lilly) | Completed (Apr 2026) |
| NCT05882045 | Obesity with cardiovascular disease (TRIUMPH-3 per Lilly) | Completed (May 2026) |
| NCT05931367 | Obesity or overweight with knee osteoarthritis (TRIUMPH-4 per Lilly) | Completed (Nov 2025) |
| NCT07629401 | Pre-approval expanded access | Available |
We list four of the 33. We did not confirm the TRIUMPH number for every record, so the trial names in the second column are the sponsor’s, not ours.
FDA statements
FDA has not reviewed retatrutide for approval. What we read is its statement on unapproved GLP-1 drugs (content current Oct 1, 2026) and two warning letters.
What FDA’s documents say
- FDA’s page says retatrutide and cagrilintide cannot be used in compounding under federal law.
- The page says FDA has warned telehealth companies for marketing unapproved drugs such as retatrutide, and active pharmaceutical ingredient distributors for selling it.
- Warning letter, Sep 9, 2025 (GLP-1 Solution): says the firm’s compounded retatrutide products are unapproved new drugs and misbranded, and fail the conditions of sections 503A and 503B. FDA letter 715883
- Warning letter, Aug 24, 2026 (Royal Peptides LLC): lists retatrutide among seven products FDA treats as unapproved new drugs despite “research use only” labeling. FDA letter 734884
What we did not find
- We found no FDA briefing document or advisory committee review of retatrutide.
- A warning letter is FDA’s statement about one firm’s conduct on one date. It is not a finding about the substance.
- We did not open other 2025 and 2026 letters that may name it.
Published research and sponsor results
PubMed returns 211 results for retatrutide as of Nov 1, 2026.
What the sources show
- Phase 2, obesity, 2023. Triple-hormone-receptor agonist for obesity. N Engl J Med PubMed
- Phase 2, type 2 diabetes, 2023. Lancet PubMed
- Phase 3 TRIUMPH-2, 2026. Retatrutide in adults with obesity and type 2 diabetes. Lancet PubMed
- Company release, July 23, 2026. Reports average weight loss of 20.8% (TRIUMPH-2, 12 mg, 80 weeks) and up to 22.6% (TRIUMPH-3), and says Lilly plans a BLA submission in Q1 2027. Press release (BioSpace)Manufacturing Chemist
Read with care
- Weight-loss averages are from trial participants, under medical supervision, on pharmaceutical-grade product. They say nothing about product sold online.
- We read titles and company releases, not full text of the papers.
- Trial figures come from the company’s own announcement; we found no independent summary of TRIUMPH-3.
Timeline
Newest first. Every entry links to the document it comes from.
- Government or registry record
- Journal
- Oct 30, 2026RegulatoryHHS publishes draft policy pausing enforcement on six peptides; retatrutide is not one of them
The draft policy’s appendix names six peptides: BPC-157, TB-500, epitalon, Semax, KPV and MOTS-c. We read the appendix through a text extraction.
- Oct 10, 2026LiteratureTRIUMPH-2 published in Lancet
Retatrutide in adults with obesity and type 2 diabetes.
- Oct 1, 2026RegulatoryFDA page states retatrutide cannot be used in compounding
It also says FDA has warned telehealth firms and API distributors.
- Aug 24, 2026EnforcementFDA warning letter to Royal Peptides LLC lists retatrutide among unapproved new drugs
The letter cites the firm’s website, a peptide calculator and bacteriostatic water sales.
- July 23, 2026SponsorLilly reports TRIUMPH-2 and TRIUMPH-3 results and a planned Q1 2027 BLA submission
Company press release as reposted by BioSpace.
- Sep 9, 2025EnforcementFDA warning letter to GLP-1 Solution says compounded retatrutide is an unapproved new drug
The letter also says the products fail the conditions of sections 503A and 503B.
- 2023LiteraturePhase 2 trials in obesity and in type 2 diabetes
Published in N Engl J Med and Lancet.
Still not covered
Left off rather than guessed:
- Whether it is on FDA’s bulks page: we read the page (content current Apr 22, 2026); retatrutide is not listed. The page predates the July panel and the Oct 30 policy.
- Primary Lilly releases: we read the July 23 release as reposted, and did not open Lilly’s own site (it refused our request). TRIUMPH-1 and TRIUMPH-4 figures are not given here because we did not verify them.
- Reported deaths and lawsuits: trade press reports FDA received death reports after use of counterfeit product and that Lilly filed lawsuits in Aug 2026. We did not read the underlying records and do not state them as fact.
- HHS policy: we read the draft policy appendix through a text extraction, not the original PDF layout. It names six covered peptides and not this drug.
- Patents, SEC filings and sponsor results releases: not researched for this dossier, except where cited.
- Seller claims and independent lab reports: how gray-market product is marketed versus what testing finds. We have not collected testing data.
- Unread items: full text of every paper; EU and other non-US regulators; WADA’s own file for the 2026 list; FDA warning letters other than those listed.