Retatrutide

Eli Lilly's investigational triple agonist. Not approved anywhere

By MoveWell Research Team Updated November 1, 2026
Schematic, not a structure: retatrutide activating the GIP, GLP-1 and glucagon receptors
Retatrutide receptor schematic (sequence not verified)Details and downloads
Evidence4/5Strong human trials, not approved
Status nowNot approved by FDA or any other regulator. In phase 3 trials.1 Anything sold today is unapproved, and FDA recommends that consumers not buy it.2
LatestOctober 28, 2026: Lilly reported by press release that retatrutide beat Ozempic 2 mg in type 2 diabetes (TRANSCEND-T2D-2).1 On September 29, 2026, TRIUMPH-1 was published in NEJM and TRIUMPH-2 in the Lancet.3, 4
NextLilly plans to submit a Biologics License Application to FDA in Q1 2027. It has given no approval date.5 Full history

Retatrutide is an investigational once-weekly injection from Eli Lilly that activates three hormone receptors: GIP, GLP-1 and glucagon. It is not approved anywhere. In TRIUMPH-1, published in NEJM, people on 12 mg lost 25.0% of body weight over 80 weeks, vs 3.9% on placebo.3 The only legal way to take it is in a clinical trial.

Retatrutide can't be bought legally. Vials sold online, including those labeled "research use only," are unapproved. FDA has called such products "unapproved new drugs" and recommends that consumers not buy them.2, 6 FDA warnings

In this guide
  1. Status and summary
  2. At a glance
  3. Where to get it
  4. Approval and FDA warnings
  5. Molecular structure
  6. How it works
  7. Trial results
  8. Safety signals
  9. Compared with
  10. Myths vs evidence
  11. Status history
  12. FAQ
  13. References

At a glance

What it isA peptide that activates GIP, GLP-1 and glucagon receptors, a "triple agonist"7, 5
StatusInvestigational. Phase 3. Lilly plans to file with FDA in Q1 20275
TakenWeekly injection under the skin, in trials. No approved dose8
Best evidenceTwo published phase 2 trials and two published phase 3 trials: TRIUMPH-1 (n=2,339) and TRIUMPH-2 (n=1,152)8, 7, 3, 4
Weight loss in trials−25.0% vs −3.9% on placebo at 80 weeks on 12 mg (TRIUMPH-1)3
Main risksNausea, diarrhea, constipation, vomiting; abnormal skin sensation (dysesthesia); an early rise in heart rate9, 8
CostNo lawful price. It isn't sold legally anywhere2

Where to get it

MoveWell sells nothing. There is no legal way to buy retatrutide, so this page links to no sellers.

The only legal routeA clinical trial

Lilly is still running retatrutide trials, including TRIUMPH-5 against tirzepatide.1 Search for open studies near you and ask your doctor whether one fits.

Search ClinicalTrials.gov
Approved todayTirzepatide

Lilly's approved dual agonist, sold as Mounjaro and Zepbound, with prescription and self-pay options.10, 11

Tirzepatide guide
Approved todaySemaglutide

Sold as Ozempic, Wegovy and Rybelsus, as weekly injections and daily tablets.12

Semaglutide guide

Not listed: any seller of retatrutide, compounded or "research use only." Why

Approval and FDA warnings

Where approval stands

  • Not approved anywhere. Lilly's October 28, 2026 release calls retatrutide investigational and uses "if approved" language.1
  • Filing planned for Q1 2027. Lilly says it plans to submit a Biologics License Application (BLA) to FDA in Q1 2027, after completing its manufacturing data package.5 It has not given an expected approval date.
  • Six phase 3 trials reported so far, two of them peer reviewed (see trial results).1, 3, 4

What FDA has said and done

  • No compounding path. In an April 2, 2025 letter to the Federation of State Medical Boards, FDA said compounded retatrutide does "not currently meet the requirements for exemptions under sections 503A or 503B," and recommended that "consumers not purchase unapproved products containing retatrutide."2
  • Warning letters. On December 10, 2024, FDA warned at least three online sellers that their retatrutide products were "unapproved new drugs" despite research-only labels, because they were intended for human use, and warned of possible seizure and injunction.6, 13, 14 On August 24, 2026, it sent five more letters to websites selling some combination of semaglutide, tirzepatide and retatrutide.15 See the regulatory tracker.
  • An advocacy group's count. Public Citizen counted 14 FDA warning letters to retatrutide sellers since 2024, found 8 of those companies still selling it as of May 2026, and found 14 hospitalizations linked to retatrutide in FDA's adverse-event database. That is Public Citizen's analysis, not an FDA tally.16
  • No import alert names it. FDA's import alert on bulk GLP-1 ingredients does not list retatrutide.17

Other actions

  • Lilly lawsuits. In Aug 2026, Lilly sued six companies it says sold counterfeit, unapproved retatrutide falsely labeled "research-use only." This is private litigation, not an FDA action.18
  • Liver injury in Australia. On June 19, 2026, the Chief Health Officer of Victoria reported six cases of acute liver injury across Australia since Jan 2026 linked to products labeled retatrutide, possibly from a contaminant; testing was under way.19 It shows that what's in gray-market vials is unknown; it is not evidence about retatrutide itself.

Molecular structure

A schematic, not a structure. Retatrutide is a peptide that activates GIP, GLP-1 and glucagon receptors.7 We haven't confirmed its full sequence from a primary source, so the diagram shows only the three receptors it targets.

SCHEMATIC · NOT A MOLECULAR STRUCTURE Retatrutide one peptide · sequence not shown GIP receptor GLP-1 receptor Glucagon receptor Triple agonist: activates all three receptors Investigational · not approved anywhere

The three receptors retatrutide activates

Class
GIP, GLP-1 and glucagon receptor agonist
Taken
Weekly injection (trials)
Identifiers
Not confirmed from a primary source
Half-life
Not in our sources

Class is from the published phase 2 trials; weekly dosing from the phase 2 obesity trial.7, 8 Its formula, molecular weight and other identifiers are not confirmed from a primary source, so we don't list them.

How it works

Retatrutide activates three receptors.7 Two are the same as tirzepatide's; the third is new among these drugs:

  • GLP-1 receptor. The target of semaglutide.12
  • GIP receptor. The second target of tirzepatide, which acts on both GIP and GLP-1.20
  • Glucagon receptor. Retatrutide's addition, which makes it a "triple agonist."7, 5

Whether the third receptor adds benefit beyond tirzepatide is untested: the head-to-head trial, TRIUMPH-5, has not reported.1

Trial results

Peer-reviewed results first. Press-release results are labeled; they have not been through peer review.

Weight loss, obesity

Strong human: TRIUMPH-1 (n=2,339, NEJM) and phase 2 (n=338). Not approved

Type 2 diabetes

Strong human: TRIUMPH-2 (n=1,152, Lancet), phase 2 (n=281), TRANSCEND-T2D-1 and -2 (press releases). Not approved

Sleep apnea

Limited human: one pre-specified substudy of TRIUMPH-1 (n=243). Not approved

Knee osteoarthritis pain

Limited human: one trial, TRIUMPH-4 (n=445), press release only

Heart attack and stroke risk

Not graded No heart-outcome trial result yet. TRIUMPH-3's pre-planned heart-event analyses were not significant

Scale: 5 FDA-approved, 4 strong human, 3 limited human, 2 animal or lab only, 1 anecdotal.

Peer reviewed

TrialPopulationModelFinding
TRIUMPH-1 (NEJM, September 29, 2026)3Obesity or overweight, no diabetes; 80 weeksHuman RCT n=2,33912 mg: −25.0% vs −3.9% on placebo, counting everyone who started (the primary result; a 21.0-point difference)
TRIUMPH-1 sleep apnea substudy3, 21Obesity with sleep apnea; 80 weeksHuman RCT n=24312 mg: breathing events (AHI) −31.7 vs −9.9 per hour on placebo. First presented at ADA, Jun 2026
TRIUMPH-2 (Lancet, September 29, 2026)4, 5Obesity with type 2 diabetes; 80 weeksHuman RCT n=1,152−11.9%, −16.8% and −18.8% (4, 9, 12 mg) vs −5.1% on placebo, counting everyone who started (the primary result; a 13.8-point difference on 12 mg, 95% CI 11.8–15.8). Lilly's press release reported −12.7%, −19.1% and −20.8% vs −4.0%, and A1C −1.4 to −1.6 points vs −0.2, counting people who stayed on treatment
Phase 2, obesity (NEJM 2023)8Obesity, no diabetes; 48 weeksHuman RCT n=338−8.7%, −17.1%, −22.8% and −24.2% (1, 4, 8, 12 mg) vs −2.1%. At least 15% loss: 60%, 75% and 83% (4, 8, 12 mg) vs 2%
Phase 2, type 2 diabetes (Lancet 2023)7Type 2 diabetes, US only; 36 weeksHuman RCT n=281A1C down up to 2.02 points at 24 weeks vs 0.01 on placebo and 1.41 on dulaglutide. Weight up to −16.94% at 36 weeks vs −3.00% and −2.02%

Press releases (not peer reviewed)

TrialPopulationModelFinding
TRANSCEND-T2D-2 (October 28, 2026)1, 22Type 2 diabetes on metformin, with or without an SGLT2 inhibitor; vs Ozempic 2 mg; 80 weeks, open labelPress release n=1,298A1C −2.2 points (9 and 12 mg) vs −1.8. Weight −19.5% and −20.9% vs −9.4%, counting people who stayed on treatment. Ozempic 2 mg is a diabetes dose, not Wegovy's weight dose23, 12
TRIUMPH-3 (July 23, 2026)5BMI 35 or more with heart disease; 80 weeksPress release n=1,949Weight −21.6% and −22.6% (9, 12 mg) vs −3.2%. Pre-planned heart-event analyses not significant: MACE-5 HR 0.82 (0.55–1.22), MACE-3 HR 1.12 (0.64–1.96). Not a heart-outcome trial
TRANSCEND-T2D-1 (March 19, 2026)24Type 2 diabetes on diet and exercise; 40 weeksPress release n=537A1C −1.7 to −2.0 points vs −0.8. Weight −11.5%, −15.5% and −16.8% (4, 9, 12 mg) vs −2.5%
TRIUMPH-4 (December 11, 2025)25Obesity with knee osteoarthritis; 68 weeksPress release n=445Weight −26.4% and −28.7% (9, 12 mg) vs −2.1%. Knee pain (WOMAC) −75.8% and −74.3% vs −40.3%
TRIUMPH-1 topline (May 21, 2026)9As abovePress release n=2,339Counting everyone: −17.6%, −23.7%, −25.0% (4, 9, 12 mg) vs −3.9%. Counting only people who stayed on treatment: up to −28.3% vs −2.2%. Extension in BMI 35 or more (n=532), 104 weeks: up to −30.3% counting people who stayed on treatment (−29.9% counting everyone)
TRIUMPH-51Obesity; vs tirzepatideOngoingNo results yet

"Counting everyone who started" (treatment-regimen estimand) gives smaller numbers than "counting people who stayed on treatment" (efficacy estimand). Lilly's May 2026 TRIUMPH-1 release led with the second. Numbers from separate trials can't be ranked against each other: lengths, populations and analysis methods differ.

Safety signals

No labelRetatrutide has no FDA label, so no boxed warning or approved list of warnings has been set. What's known comes from trials.
Gray marketProducts sold online may not contain what they claim. Victoria's health department reported six cases of liver injury across Australia linked to products labeled retatrutide, possibly from a contaminant.19

Stomach side effects

Common and dose-dependent, mostly while the dose is going up. TRIUMPH-1, 12 mg vs placebo:9

ReactionRetatrutide 12 mgPlacebo
Nausea42.4%14.8%
Diarrhea32.0%13.5%
Constipation26.1%10.9%
Vomiting25.3%4.8%

From Lilly's press release; not yet checked against the NEJM paper.9 In phase 2, 45% had nausea and 19% vomiting on 12 mg.8

Dysesthesia (abnormal skin sensation)

Tingling or touch-sensitive skin. Lilly describes the events as mostly mild to moderate and resolving.9

TrialRetatrutideComparison
Phase 2, obesity7%1% placebo; none severe8
TRIUMPH-15.1%, 12.3%, 12.5% (4, 9, 12 mg)0.9% placebo9
TRIUMPH-48.8%, 20.9% (9, 12 mg)0.7% placebo25
TRIUMPH-24.5% to 7.3%0.7% placebo5
TRIUMPH-36.4%1.3% placebo5
TRANSCEND-T2D-24.8%, 6.5% (9, 12 mg)2.7% Ozempic1

Heart rate and rhythm

  • Heart rate. In the phase 2 obesity trial, heart rate rose with dose, peaked at 24 weeks, then declined.8 In the phase 2 diabetes trial it rose up to about 7 beats a minute early on; at 36 weeks the change was +0.03 to +4.34 vs −3.16 on placebo and +1.76 on dulaglutide.7 The peak value in the obesity trial and any phase 3 heart-rate data aren't in our sources.
  • Arrhythmia. 6% vs 3% on placebo in phase 2, mild to moderate. One severe prolonged-QT event occurred in a person also taking ondansetron.8
  • Heart outcomes. No result from a dedicated heart-outcome trial yet; TRIUMPH-3's pre-planned analyses were not significant (HR 0.82 and 1.12).5

Stopping and other effects

  • Stopped for side effects. TRIUMPH-1: 4.1%, 6.9% and 11.3% (4, 9, 12 mg) vs 4.9%.9 TRIUMPH-4: 12.2% and 18.2% (9, 12 mg) vs 4.0%; Lilly says this was higher in people with a lower starting BMI and included stopping for "perceived excessive weight loss."25 TRANSCEND-T2D-2: 7.9% on 12 mg vs 2.7% on Ozempic.1
  • Urinary tract infections. 6.8% to 8.1% vs 4.8% in TRIUMPH-1, 92% of them in women.26
  • Low blood pressure. Reported, more often in people taking blood pressure medicines.26
  • Serious adverse events. 7.7% to 10.5% vs 5.5% in TRIUMPH-1.26

Compared with

RetatrutideTirzepatideSemaglutide
TargetsGIP, GLP-1 and glucagon7GIP and GLP-120GLP-112
StatusNot approved; filing planned Q1 20275FDA-approved (Mounjaro, Zepbound)10, 11FDA-approved (Ozempic, Wegovy, Rybelsus)12
Weight loss, main trial−25.0% vs −3.9% at 80 weeks (TRIUMPH-1)3−20.9% vs −3.1% at 72 weeks (SURMOUNT-1)27−14.9% vs −2.4% at 68 weeks (STEP 1)28
Head to headvs tirzepatide: TRIUMPH-5 ongoing. vs Ozempic 2 mg in diabetes: −20.9% vs −9.4% (press release)1SURMOUNT-5: tirzepatide −20.2% vs semaglutide −13.7%29
Stands outDysesthesia, up to 20.9% at 12 mg in one trial25Hair loss 4% to 5% vs 1%20The only one with a pill12
Legal to buyNo; clinical trials only2Yes, with a prescription30Yes, with a prescription12

Without a head-to-head trial against tirzepatide, the best overview is a 2025 review of 26 trials in about 15,491 adults without diabetes. Placebo-adjusted weight loss was about 22% for retatrutide 12 mg (one 48-week phase 2 trial), 18% for tirzepatide 15 mg and 14% for semaglutide 2.4 mg.31 The trials were too different to pool, and the retatrutide figure predates phase 3.32 Full side-by-sides: tirzepatide vs retatrutide, semaglutide vs retatrutide and the three-way comparison.

Myths vs evidence

Claim"Research use only" retatrutide is legal to buy
EvidenceFDA has called these products "unapproved new drugs" because they are intended for people, whatever the label says, and recommends that consumers not buy them.6, 13, 2
ClaimA compounding pharmacy can make it legally
EvidenceFDA says compounded retatrutide does not meet the requirements for the 503A or 503B exemptions.2
ClaimIt's already approved, or about to be
EvidenceIt isn't approved anywhere. Lilly plans to file in Q1 2027 and has given no approval date.5, 1
ClaimIt's proven better than tirzepatide
EvidenceThey haven't been compared. TRIUMPH-5 is testing that now; separate trials can't settle it.1, 32
ClaimThe results are just press releases
EvidenceNot all of them. Both phase 2 trials, TRIUMPH-1 (NEJM) and TRIUMPH-2 (Lancet) are peer reviewed. Other phase 3 results are so far press releases.8, 3, 4
ClaimA vial labeled retatrutide contains retatrutide
EvidenceNot guaranteed. Lilly alleges some sellers sold counterfeit product, and Australian officials linked liver injuries to labeled products, possibly from a contaminant.18, 19
ClaimIt's just a stronger Ozempic
EvidenceIt acts on two more receptors than semaglutide and has its own side effect, dysesthesia, in up to 20.9% at 12 mg in one trial.7, 25

FAQ

Is retatrutide FDA-approved?

No. It isn't approved anywhere. It's in phase 3 trials.

When will it be approved?

Nobody knows yet. Lilly plans to submit its application to FDA in Q1 2027 and hasn't given an approval date.

Can I buy retatrutide online?

Not legally. Anything sold today is unapproved, FDA recommends that consumers not buy it, and products labeled retatrutide have been linked to liver injury in Australia.

Is "research use only" retatrutide legal?

No. FDA has told sellers that products intended for people are unapproved new drugs, whatever the label says.

How can I get it legally?

Only in a clinical trial. Search ClinicalTrials.gov and ask your doctor. Approved alternatives today are tirzepatide and semaglutide.

How much weight did people lose?

In TRIUMPH-1, published in NEJM, 25.0% on 12 mg vs 3.9% on placebo over 80 weeks, counting everyone who started. Lilly's press release also gave up to 28.3% counting only people who stayed on treatment.

Is it stronger than tirzepatide?

Unknown. They haven't been compared directly; TRIUMPH-5 is testing that now.

What side effects does it cause?

Mostly nausea, diarrhea, constipation and vomiting. It also causes dysesthesia, an abnormal skin sensation such as tingling, in some people, and heart rate rose early in phase 2.

Has it been peer reviewed?

Partly. Both phase 2 trials and two phase 3 trials (TRIUMPH-1 in NEJM and TRIUMPH-2 in the Lancet) are published. Other phase 3 results are so far Lilly press releases.

Who makes it?

Eli Lilly, the maker of tirzepatide (Mounjaro and Zepbound).

References

32 sources, with links
  1. Eli Lilly press release. TRANSCEND-T2D-2: retatrutide vs Ozempic 2 mg, topline results (Oct 28, 2026). Not peer reviewed. Link
  2. FDA letter to the Federation of State Medical Boards on retatrutide (Apr 2, 2025), posted by the Arizona Board of Osteopathic Examiners. Link
  3. Jastreboff AM, Kaplan LM, Davies MJ et al. Retatrutide, a triple hormone receptor agonist, for treatment of obesity (TRIUMPH-1). NEJM, published online Sep 29, 2026. doi:10.1056/NEJMoa2604169. Summary: GPnotebook
  4. Bellido V, le Roux CW, Ekinci EI et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2). Lancet, published online Sep 29, 2026. doi:10.1016/S0140-6736(26)01861-1. Summary: Cardioteca
  5. Eli Lilly press release (via BioSpace). TRIUMPH-2 and TRIUMPH-3 topline results; BLA submission planned for Q1 2027 (Jul 23, 2026). Link
  6. FDA warning letter. Swisschems (Dec 10, 2024). fda.gov
  7. Rosenstock J et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a phase 2 trial. Lancet 2023 (online Jun 26, 2023). doi:10.1016/S0140-6736(23)01053-X. Author PDF
  8. Jastreboff AM et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. NEJM 2023 (online Jun 26, 2023). doi:10.1056/NEJMoa2301972. Author PDF
  9. Eli Lilly press release. TRIUMPH-1 topline results (May 21, 2026). Link
  10. BioSpace (FDA release). FDA approves novel, dual-targeted treatment for type 2 diabetes (May 13, 2022). Link
  11. BioSpace (FDA release). FDA approves new medication for chronic weight management (Nov 8, 2023). Link
  12. FDA. Wegovy (semaglutide) injection and tablets, prescribing information, revised 05/2026. PDF
  13. FDA warning letter. Prime Vitality Inc. dba Prime Peptides (Dec 10, 2024). fda.gov
  14. FDA warning letter. Summit Research Peptides (Dec 10, 2024). fda.gov
  15. pharmaphorum. FDA issues warning letters to five unapproved GLP-1 websites (Sep 2, 2026; letters dated Aug 24, 2026). Link
  16. Public Citizen. Hospitalizations, enforcement gaps and influencers tied to unapproved retatrutide products (Jun 16, 2026). Advocacy-group analysis. Link
  17. FDA. Import Alert 66-80, detention of GLP-1 bulk drug substances (revised Oct 9, 2026). fda.gov
  18. Healio. Eli Lilly files lawsuits against six companies for allegedly selling retatrutide (Aug 14, 2026). Link
  19. Victoria Department of Health. Toxicity linked to unapproved peptide product labelled retatrutide (Jun 19, 2026). Link
  20. FDA. Zepbound (tirzepatide) prescribing information, revised 04/2026. PDF
  21. HCPLive. Retatrutide improves weight loss, knee osteoarthritis pain, sleep apnea versus placebo (TRIUMPH-1, NEJM; Sep 29, 2026). Link
  22. STAT. Retatrutide vs Ozempic: Lilly diabetes study (Oct 28, 2026). Link
  23. FDA. Ozempic (semaglutide) injection, prescribing information, revised 05/2026. PDF
  24. Eli Lilly press release. TRANSCEND-T2D-1 topline results (Mar 19, 2026). Link
  25. Eli Lilly press release. TRIUMPH-4 topline results (Dec 11, 2025). Link
  26. Eli Lilly (for health care professionals). TRIUMPH-1 presentation, ADA 2026. Link
  27. Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). NEJM 2022;387:205–16. Ovid
  28. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). NEJM 2021;384:989–1002. Abstract: J Endocr Soc 2021;5(Suppl 1):A10. PMC8089593
  29. American College of Cardiology journal scan. SURMOUNT-5 (Aronne, NEJM 2025;393:26–36; Jul 10, 2025). Link
  30. LillyDirect. Zepbound self-pay pricing (page dated Sep 2, 2026; checked Nov 1, 2026). Link
  31. Drugs.com / HealthDay. Some GLP-1s achieve more weight loss than others (on Moiz et al., Ann Intern Med, Jan 2025). Link
  32. TheNNT. Efficacy of tirzepatide, retatrutide and semaglutide for weight loss in obese individuals without diabetes (review of Moiz et al.). Link

This page is for education and is not medical advice. Retatrutide is not approved and is available only in clinical trials. Talk to a clinician before starting, stopping or switching any weight-loss or diabetes drug.