General information with sources. Never a substitute for your doctor.

MethodologyAbout the authorESEN
SaciedadSearch

GLP-1News

Retatrutide: What It Is, Where the Trials Stand and Why It Isn't Sold (2026)

Retatrutide, Eli Lilly's triple agonist, is not approved anywhere. Phase 2 and 3 results with their source, regulatory status, and why there is no price or legal sale.

Written by
Published
Next review
Sources
19 primary and 5 supporting

No clinical review. No advertising from drug companies and no affiliate links.How we work

As of September 24, 2026, retatrutide is an investigational drug from Eli Lilly: a once-weekly injection that activates the receptors for three hormones at once (GIP, GLP-1 and glucagon). It is not approved in any country, so it has no price, and anything sold online as retatrutide is not an approved medicine[8]. Lilly plans to apply for US approval in the first quarter of 2027[7]. On September 29, 2026, its first two phase 3 obesity trials were published in peer-reviewed journals. In the larger one, TRIUMPH-1, the 12 mg dose lowered body weight by an average of 25.0% over 80 weeks, versus 3.9% on placebo, counting every participant whether or not they stayed on treatment[23].

This is general information, not treatment guidance. If you are considering this or any other medication, talk to your doctor.

In 30 seconds

  • Not approved in any country[8]. Lilly plans to apply for US approval in the first quarter of 2027[7].
  • TRIUMPH-1, published in NEJM in September 2026: −25.0% body weight on 12 mg at 80 weeks, versus −3.9% on placebo, with every participant in the analysis[23].
  • In type 2 diabetes, TRIUMPH-2, published in The Lancet the same day: −18.8% on 12 mg at 80 weeks, versus −5.1%, with the same analysis[24].
  • There are no results yet from a head-to-head trial against tirzepatide. The trial that does it, TRIUMPH-5, is still running[9].
  • The FDA, Argentina’s ANMAT and Colombia’s INVIMA have warned about unauthorized retatrutide sold online142122.

What retatrutide is

Retatrutide (code name LY3437943) is a peptide, a short chain of amino acids, injected under the skin once a week[2]. According to Lilly, it is a single molecule that activates three receptors: those for GIP, GLP-1 and glucagon[7]. That is why it is called a triple agonist.

Semaglutide (Ozempic, Wegovy) activates only the GLP-1 receptor. Tirzepatide (Mounjaro, Zepbound) activates the GIP and GLP-1 receptors. Retatrutide adds the glucagon receptor. Why it makes sense to add a hormone that raises blood sugar is explained in what GLP-1 medications are, along with the rest of the family. The generic and brand names of each drug are in GLP-1 generic and brand names.

The phase 3 trials tested weekly doses of 4, 9 and 12 mg, reached by stepping up gradually from 2 mg, according to Lilly’s releases457. There is no approved dosing schedule, because there is no label.

Where the trials stand

A drug goes through three phases of trials before approval is requested: phase 1 checks safety in a few people, phase 2 looks for the dose, and phase 3 confirms the effect in thousands of participants. Retatrutide has finished its main phase 3 obesity trials. Eli Lilly funded all of them.

One important detail before reading the numbers. Lilly’s releases lead with the efficacy estimand: what would have happened if everyone had stayed on treatment45. The treatment-regimen estimand includes every participant, whether or not they stayed on treatment, and usually gives somewhat smaller numbers. It is the main analysis in the TRIUMPH-1 and TRIUMPH-2 papers, and the one I use for them2324. When a press release gives both, I show both.

Trial Participants Length Weight change on the highest dose Placebo Type of source
Phase 2, obesity 338 adults with obesity or overweight, no diabetes 48 weeks −24.2% (12 mg) −2.1% Paper in NEJM (2023)[1]
Phase 2, type 2 diabetes 281 adults with type 2 diabetes 36 weeks −16.94% (12 mg) −3.00% Paper in The Lancet (2023)[2]
TRIUMPH-4 445 adults with obesity or overweight and knee osteoarthritis, no diabetes 68 weeks −28.7% (12 mg; −23.7% treatment-regimen) −2.1% (−4.6%) Press release (December 2025)[4]
TRANSCEND-T2D-1 537 adults with type 2 diabetes managed with diet and exercise alone 40 weeks −15.3% (12 mg) −2.6% Paper in The Lancet (2026)[3]
TRIUMPH-1 2,339 adults with obesity, or overweight and at least one related condition, no diabetes 80 weeks −25.0% (12 mg) −3.9% Paper in NEJM (2026)[23]
TRIUMPH-2 1,152 adults with type 2 diabetes and obesity or overweight (BMI of 27 or more) 80 weeks −18.8% (12 mg) −5.1% Paper in The Lancet (2026)[24]
TRIUMPH-3 1,949 adults with a BMI of 35 or more and established cardiovascular disease 80 weeks −22.6% (12 mg) −3.2% Press release (July 2026)[7]

BMI: body mass index, in kg/m². Press-release figures (TRIUMPH-4 and TRIUMPH-3): efficacy estimand (treatment-regimen in parentheses, when the release gives it); TRANSCEND-T2D-1, TRIUMPH-1 and TRIUMPH-2 papers: treatment-regimen estimand. Participants randomized according to Lilly or the paper; the ClinicalTrials.gov registry lists 2,335 for TRIUMPH-1 and 1,946 for TRIUMPH-3. I have summarized four of the trials published in journals: retatrutide phase 2, TRANSCEND-T2D-1, TRIUMPH-1 and TRIUMPH-2, in the studies section.

  • Phase 2 in obesity. Weight fell by 8.7%, 17.1%, 22.8% and 24.2% at 48 weeks on 1, 4, 8 and 12 mg. On 12 mg, 83% lost at least 15% of their weight, versus 2% on placebo[1]. The groups were small and this was a phase 2 trial, designed to find the dose.
  • Phase 2 in type 2 diabetes. At 24 weeks, HbA1c (glycated hemoglobin, a measure of average blood sugar over the past few months) fell by 2.02 points on 12 mg, versus 1.41 on dulaglutide 1.5 mg and 0.01 on placebo[2]. Dulaglutide is an approved GLP-1 medication (Trulicity).
  • TRIUMPH-4 (press release). Besides weight, it measured knee pain on the WOMAC scale, from 0 to 10. From a starting score of 6.0, pain fell by 4.5 points on 9 mg and 4.4 on 12 mg, versus 2.4 on placebo[4].
  • TRANSCEND-T2D-1. The first phase 3 trial published in a peer-reviewed journal. HbA1c fell by 1.69, 1.86 and 1.94 points on 4, 9 and 12 mg, versus 0.81 on placebo. Weight changed by −11.5%, −13.9% and −15.3%, versus −2.6%[3].
  • TRIUMPH-1. On 4 and 9 mg, weight fell by 17.6% and 23.7%. Compared with placebo, the difference was −19.8 percentage points on 9 mg and −21.0 on 12 mg[23]. The trial included two sub-studies, which Lilly presented at the American Diabetes Association meeting in June 2026[6] and which the paper now reports. In 574 participants with knee osteoarthritis, pain (WOMAC scale) fell by 3.9 and 4.1 points on 9 and 12 mg, versus 2.5 on placebo. In 243 with obstructive sleep apnea, the apnea-hypopnea index (breathing pauses and reductions per hour of sleep) fell by 34.3 and 32.1 events per hour, versus 9.6. These figures use the same analysis as weight; the sub-studies’ main analysis, with a different estimand, gave differences versus placebo of −1.6 and −1.8 points for pain and −24.4 and −21.9 events per hour[23].
  • TRIUMPH-1, what is only in the press release. With the efficacy estimand, 45.3% of those on 12 mg lost at least 30% of their weight, versus 0.5% on placebo. In an extension with 532 participants who started with a BMI of 35 or more, had completed the 80 weeks and tolerated their dose, weight loss reached 30.3% at 104 weeks on 12 mg[5]. These figures do not appear in the paper’s abstract.
  • TRIUMPH-2. It ran at 92 sites in eight countries, in people managed with diet and exercise alone or with up to three oral diabetes drugs; they started at a mean BMI of 38.2 and a mean HbA1c of 7.71%. On 4 and 9 mg, weight fell by 11.9% and 16.8%. Compared with placebo, the difference on 12 mg was −13.8 percentage points (95% CI, −15.8 to −11.8)[24]. The paper’s abstract says blood sugar control improved but gives no figure; according to Lilly’s release, with the efficacy estimand, HbA1c fell by 1.4 to 1.6 points, versus 0.2 on placebo[7]. As with the other drugs in the family, people with type 2 diabetes lose less weight.
  • TRIUMPH-3 (press release). On 9 mg, weight fell by 21.6%. Serious cardiovascular events were less frequent than expected in both groups, and the comparison with placebo was inconclusive. The hazard ratio (below 1 means fewer events on retatrutide) was 0.82 (95% CI, 0.55 to 1.22) for the broad set: death from any cause, heart attack, stroke, heart failure event or coronary revascularization. For the strict set (cardiovascular death, heart attack or stroke) it was 1.12 (95% CI, 0.64 to 1.96)[7]. A 95% CI (confidence interval) is the range where the true effect probably lies, and both include 1, which means no difference.

What is missing. TRIUMPH-1 and TRIUMPH-2 were published on September 29, 2026, in The New England Journal of Medicine and The Lancet, so their figures have now been through peer review2324. As of October 5, 2026, I have not found papers for TRIUMPH-3 or TRIUMPH-4 on PubMed: for those two there are only press releases47. A press release is written by the company, and no outside reviewer has yet checked the methods or the full analysis. Other trials are still running, including one on cardiovascular and kidney outcomes with an estimated primary completion date of February 2029, according to its registry entry[10].

Is it approved? Regulatory status by country

Region Status as of September 24, 2026 Source
United States Not approved. Lilly plans to submit its application to the FDA in the first quarter of 2027 Lilly, July 2026[7]; FDA[14]
European Union and Spain Not approved. Not on the EMA’s list of medicines under evaluation, nor in CIMA, the Spanish regulator’s database EMA[16]; CIMA[18]
Mexico I have not found any COFEPRIS registration. Lilly says it is legally available only to participants in its trials Lilly, September 2026[8]
Argentina Not approved: ANMAT describes it as a substance under clinical investigation ANMAT[21]
Colombia No marketing authorization, according to an INVIMA alert INVIMA[22]

The FDA sums it up: retatrutide is not a component of any FDA-approved drug, has not been found safe and effective for any condition, and cannot be used in compounding under federal law[14].

Outside the trials, Lilly registered a pre-approval expanded access program in June 2026: case-by-case use, requested by a doctor, limited to adults with severe obesity and serious complications who have not responded to approved treatments and cannot join a trial[11]; it is not a sale.

Retatrutide price and where it is sold

There is no price because there is no legal product. Lilly does not sell retatrutide anywhere, and its July 2026 release says it cannot be legally sold or marketed for human use[7]. Any price you see online belongs to something else.

What is offered on websites, social media and messaging apps is usually presented as a “research peptide,” sometimes under names like “GLP-3.”1415 This is what regulators say:

  • FDA (United States). It has warned companies that sold retatrutide labeled “for research purposes” or “not for human consumption” but aimed at people and sold with dosing instructions. It describes these products as being of unknown quality and possibly harmful, and urges consumers not to buy them[14]. In a warning letter dated August 24, 2026, about a product called “GLP-3 Reta (Retatrutide),” it notes that also selling the water used to dissolve the vial shows the product is meant to be injected[15].
  • ANMAT (Argentina). On September 4, 2026, it expanded an alert about injectable peptides sold online and over WhatsApp, retatrutide among them. Their manufacturer, composition and production conditions are unknown, and a contaminated injectable could have serious consequences[21].
  • INVIMA (Colombia). Alert 181-2026, dated June 23, 2026, flags a “Retatrutide 10 mg/mL” vial offered on Instagram as a weight-loss treatment, with no marketing authorization and no evaluation of quality, safety or efficacy[22].
  • AEMPS (Spain). It relays the warning from the EMA and the European medicines agencies network (HMA) of a sharp rise in illegal products sold as GLP-1 medications, which may not contain the declared ingredient and may contain harmful levels of other substances[19]. In Spain, prescription medicines cannot be sold online[19].
  • COFEPRIS (Mexico). I have not found an alert specific to retatrutide. In an alert on tirzepatide dated February 9, 2026, a cartridge labeled as tirzepatide actually contained semaglutide and showed bacterial growth[20]. It shows the risk of these products, whatever the label says.

If you have already used one of these products, tell your doctor, especially if you have symptoms. Regulators also ask people to report side effects: in the US, through the FDA’s MedWatch program142022.

Retatrutide vs. tirzepatide

No head-to-head comparison has been published. The trial that pits them against each other, TRIUMPH-5, compares retatrutide and tirzepatide in about 800 adults with obesity over 80 weeks. According to its registry entry, it is still running, with an estimated primary completion date of November 2026[9].

Until then, trials can only be set side by side, using the same type of analysis (the treatment-regimen estimand):

Drug and trial Participants Length Weight on the highest dose Placebo Source
Retatrutide 12 mg, TRIUMPH-1 2,339 adults without diabetes, mean BMI 40.0 80 weeks −25.0% −3.9% Paper in NEJM (2026)[23]; BMI, press release[5]
Tirzepatide 15 mg, SURMOUNT-1 2,539 adults without diabetes, mean BMI 38.0 72 weeks −20.9% −3.1% Paper in NEJM (2022)[12]
Retatrutide 12 mg, TRIUMPH-2 1,152 adults with type 2 diabetes, mean BMI 38.2 80 weeks −18.8% −5.1% Paper in The Lancet (2026)[24]
Tirzepatide 15 mg, SURMOUNT-2 938 adults with type 2 diabetes, mean BMI 36.1 72 weeks −14.7% −3.2% Paper in The Lancet (2023)[13]

Summaries: TRIUMPH-1, TRIUMPH-2, SURMOUNT-1 and SURMOUNT-2. The rows can’t be subtracted from each other: the retatrutide trials ran eight weeks longer and their participants started at a higher BMI. Tirzepatide is an approved medicine with a label and years of use; retatrutide is not. More trial figures are charted in the trial results chart, and typical weight loss on each drug is in how much weight you lose on GLP-1s.

Other drugs in development have their own guides: survodutide, CagriSema, amycretin and maridebart cafraglutide (MariTide).

Side effects in the trials

Because there is no label, there is no official list of side effects, contraindications or warnings. This is what the papers and Lilly’s releases report:

  • Digestive. The most common in every trial. In the phase 2 obesity trial they were dose-related and mostly mild to moderate, and starting at a lower dose partly reduced them[1].
  • Heart rate. In phase 2, heart rate rose with the dose, peaked around week 24 and declined afterward[1].
  • Dysesthesia. An abnormal, unpleasant sensation in the skin. Lilly has reported it in every phase 3 trial with results, generally mild to moderate; most cases resolved during treatment457. In the TRIUMPH-2 paper it affected 4%, 6% and 7% on 4, 9 and 12 mg, versus 1% on placebo[24]. The highest figure was in TRIUMPH-4, according to its press release: 20.9% on 12 mg, versus 0.7% on placebo[4].
  • Low blood pressure. In TRIUMPH-2, hypotension was more common on retatrutide: 1%, 5% and 6% on 4, 9 and 12 mg, versus less than 1% on placebo[24].
  • Stopping treatment. In TRIUMPH-4 (press release), 18.2% on 12 mg stopped because of side effects, versus 4.0% on placebo. According to Lilly, that figure was closely tied to starting BMI and included people who felt their weight loss was excessive[4]. In TRANSCEND-T2D-1 it was 2% to 5%, versus none on placebo, and there was no severe hypoglycemia[3]. In TRIUMPH-2, 4%, 12% and 8% stopped treatment because of side effects or death on 4, 9 and 12 mg, versus 5% on placebo. There were six deaths on retatrutide and one on placebo, and the investigator judged none of them related to treatment[24].

For TRIUMPH-1, the paper’s abstract says only that the most common side effects were digestive[23]. The per-dose figures in this table come from Lilly’s press release[5]:

Side effect Placebo 4 mg 9 mg 12 mg
Nausea 14.8% 28.6% 38.4% 42.4%
Diarrhea 13.5% 25.2% 34.1% 32.0%
Constipation 10.9% 23.8% 25.9% 26.1%
Vomiting 4.8% 10.6% 22.8% 25.3%
Dysesthesia 0.9% 5.1% 12.3% 12.5%
Urinary tract infection 5.3% 7.5% 8.8% 8.4%
Stopped because of side effects 4.9% 4.1% 6.9% 11.3%

And these are the TRIUMPH-2 figures, from the abstract of its paper[24]:

Side effect Placebo 4 mg 9 mg 12 mg
Diarrhea 13% 27% 34% 34%
Nausea 8% 14% 21% 28%
Dysesthesia 1% 4% 6% 7%
Hypotension less than 1% 1% 5% 6%
Stopped because of side effects or death 5% 4% 12% 8%

These figures come from selected, closely monitored trial participants using a product made by Lilly. They say nothing about a vial bought online, whose real contents are unknown. For digestive symptoms on approved GLP-1s: what to eat with nausea and constipation on GLP-1s.

When it could reach pharmacies

Lilly has given only one date: its US application, in the first quarter of 2027. For Europe and Latin America it has not announced any; its July release mentions “global submissions” without a timeline[7].

Europe. The EMA would have to evaluate it first. According to the agency, an evaluation takes up to 210 working days, plus pauses while the company answers questions[17]. As of September 4, 2026, retatrutide was not on its list of applications under evaluation[16]. And authorization is not the same as sale: launch and, where it applies, reimbursement come afterward.

Mexico. It would need a COFEPRIS marketing authorization. I have not found any public application.

Any 2026 launch date you read is not backed by anything Lilly or the regulators have published.

Frequently asked questions

What is retatrutide and what is it used for?

It is an investigational once-weekly injection from Eli Lilly, studied for obesity, type 2 diabetes and complications such as knee osteoarthritis and sleep apnea342324. It is not approved for any of them.

How much does retatrutide cost?

It has no price: it is not legally sold anywhere, and Lilly has not announced one[7]. The prices circulating online are for unauthorized products.

Can you buy retatrutide legally?

No. It is not approved in the US, the European Union or Mexico, Lilly says it is legally available only to participants in its trials, and the FDA says it cannot be used in compounding8141618.

Is “GLP-3” the same as retatrutide?

Be careful with that name. “GLP-3” isn’t a drug class or an approved medicine: it’s a label some sellers of so-called research peptides use, sometimes for products sold as retatrutide1415. On August 24, 2026, the FDA sent a warning letter about one of them, “GLP-3 Reta (Retatrutide),” noting that the seller also offered bacteriostatic water to reconstitute its products, which showed they were meant to be injected into people[15]. The FDA describes these products, labeled “for research purposes” or “not for human consumption,” as being of unknown quality and possibly harmful, and urges consumers not to buy them[14]. Retatrutide itself is an investigational Lilly drug that activates three receptors (GIP, GLP-1 and glucagon) and isn’t approved anywhere78.

When will retatrutide be available?

Lilly plans to apply for US approval in the first quarter of 2027, and the FDA would then have to review it[7]. No date has been announced for Europe or Latin America.

Sources

Sources consulted for this article, with the access date.

  1. Clinical trialNew England Journal of Medicine.Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526.accessed .
  2. Clinical trialThe Lancet.Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. Lancet. 2023;402(10401):529-544.accessed .
  3. Clinical trialThe Lancet.Bajaj HS, et al. Efficacy and safety of retatrutide in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1). Lancet. 2026;407(10546):2402-2413.accessed .
  4. PressEli Lilly and Company (PR Newswire).Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial (TRIUMPH-4, December 11, 2025).accessed .
  5. PressEli Lilly and Company (PR Newswire).Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial (TRIUMPH-1, May 21, 2026).accessed .
  6. PressEli Lilly and Company (PR Newswire).Lilly's triple agonist, retatrutide, drove substantial improvements in weight, A1C, knee osteoarthritis pain, and obstructive sleep apnea (TRIUMPH-1 and TRANSCEND-T2D-1 at the ADA Scientific Sessions, June 6, 2026).accessed .
  7. PressEli Lilly and Company (PR Newswire).Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials (TRIUMPH-2 and TRIUMPH-3; FDA submission planned for Q1 2027) (July 23, 2026).accessed .
  8. PressEli Lilly and Company (PR Newswire).Lilly to present new data on Foundayo, retatrutide, and eloraTZP at EASD 2026 (September 15, 2026).accessed .
  9. Official databaseClinicalTrials.gov (U.S. National Library of Medicine).A Study of Retatrutide (LY3437943) Compared to Tirzepatide (LY3298176) in Adults Who Have Obesity (TRIUMPH-5), NCT06662383.accessed .
  10. Official databaseClinicalTrials.gov (U.S. National Library of Medicine).The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Outcomes in Adults Living With Obesity (TRIUMPH-Outcomes), NCT06383390.accessed .
  11. Official databaseClinicalTrials.gov (U.S. National Library of Medicine).Pre-approval Expanded Access of Retatrutide (LY3437943), NCT07629401.accessed .
  12. Clinical trialNew England Journal of Medicine.Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205-216.accessed .
  13. Clinical trialThe Lancet.Garvey WT, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. 2023;402(10402):613-626.accessed .
  14. RegulatorU.S. Food and Drug Administration (FDA).FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (content current as of September 1, 2026).accessed .
  15. RegulatorU.S. Food and Drug Administration (FDA).Warning letter to Peptide Partners LLC, 735063 (“GLP-3 Reta (Retatrutide)”) (August 24, 2026).accessed .
  16. RegulatorEuropean Medicines Agency (EMA).Applications for new human medicines under evaluation by the CHMP, September 2026 (data extracted September 4, 2026; retatrutide not listed).accessed .
  17. RegulatorEuropean Medicines Agency (EMA).The evaluation of medicines, step-by-step.accessed .
  18. Official databaseSpanish Agency of Medicines and Medical Devices (AEMPS).CIMA: search for “retatrutida”, no results on the access date.accessed .
  19. RegulatorSpanish Agency of Medicines and Medical Devices (AEMPS).La EMA y HMA advierten del aumento de medicamentos ilegales comercializados como análogos de GLP-1 (EMA and HMA warn of a rise in illegal medicines sold as GLP-1 analogues; AEMPS notice 26/2025, September 3, 2025).accessed .
  20. RegulatorFederal Commission for the Protection against Sanitary Risks (COFEPRIS, Mexico).Alerta sanitaria: comercialización ilegal de productos con tirzepatida (health alert on illegally sold tirzepatide products, February 9, 2026).accessed .
  21. RegulatorNational Administration of Drugs, Foods and Medical Devices (ANMAT, Argentina).ANMAT amplía alerta sobre productos inyectables no autorizados que contienen péptidos (alert on unauthorized injectable peptide products, September 4, 2026).accessed .
  22. RegulatorNational Food and Drug Surveillance Institute (INVIMA, Colombia).Health alert No. 181-2026: Tirzepatide injection 10 mg, Retatrutide 10 mg/mL solution for injection and other unregistered products (June 23, 2026).accessed .
  23. Clinical trialNew England Journal of Medicine.Jastreboff AM, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1). N Engl J Med. Published online September 29, 2026.accessed .
  24. Clinical trialThe Lancet.Bellido V, et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial. Lancet. Published online September 29, 2026.accessed .

Related guides

Useful tools: Monthly cost of a GLP-1Questions to ask your doctor about GLP-1