Quick answer
Retatrutide is an investigational once-weekly injectable medication being studied for obesity and related metabolic conditions. It acts on three hormone receptors: GIP, GLP-1, and glucagon. Lilly reported Phase 3 TRIUMPH-1 trial results in May 2026, but retatrutide remains investigational and is not FDA-approved. It cannot be prescribed outside of clinical trials, and no approval or availability date has been announced. Trial results should not be interpreted as a guarantee of individual outcomes or as proof that retatrutide is safer, more effective, or more appropriate than any FDA-approved medication.
Key takeaways
- Retatrutide is an investigational medication being studied for obesity and metabolic health. It is not FDA-approved and is not available for routine prescribing.
- Lilly reported Phase 3 TRIUMPH-1 results in May 2026, but the full evidence base, labeling, safety warnings, dosing, pricing, insurance coverage, and patient eligibility remain unknown unless and until FDA approval occurs.
- Reported side effects in trials have included gastrointestinal symptoms such as nausea, diarrhea, constipation, and vomiting.
- Retatrutide should not be purchased from peptide, research chemical, gray-market, or non-pharmacy sources.
- FDA-approved weight-loss medications are available now, but they are not appropriate for everyone. Treatment decisions require individualized clinical evaluation.
- Patients who want general updates may join our educational updates list. This does not create a patient-provider relationship and does not guarantee access to retatrutide or any specific medication.
Retatrutide is one of the most closely watched medications in obesity care, and the Phase 3 results released in 2026 are the reason. It is not available yet, and no one can tell you exactly when or whether it will be. This page explains what retatrutide is, what the trials have actually shown, how it fits alongside the treatments you can get today, and how to follow its progress. We keep this page updated as retatrutide moves through trials and its approval status changes.
Join the Retatrutide Education & Updates List
Retatrutide is still in clinical trials and is not available. If you would like plain-language updates from our clinic as the research develops and its approval status changes, add your name below. This is an educational list. It is not a request for treatment, and joining it does not guarantee future access to retatrutide.
We will email you plain-language updates as retatrutide moves through trials and its status changes. No health information needed.
What is retatrutide?
Retatrutide is an investigational once-weekly injectable medication being developed by Eli Lilly for chronic weight management. It is an investigational triple hormone receptor agonist, which means it acts on three receptors at once: GIP, GLP-1, and glucagon. The GLP-1 and GIP pathways are the same ones targeted by medications already on the market, while adding glucagon activity is the feature that sets retatrutide apart and is being studied for its effect on metabolism and weight. Retatrutide has not been approved by the FDA and is not available outside of clinical trials.
What did the Phase 3 TRIUMPH-1 trial show?
In Lilly's Phase 3 TRIUMPH-1 trial, announced May 21, 2026, Lilly reported average weight loss across all doses studied. TRIUMPH-1 enrolled 2,339 adults with obesity or overweight who had at least one weight-related health condition and did not have diabetes. These results were reported by Lilly and should be interpreted as trial data pending full publication, peer review if applicable, and FDA review. FDA approval decisions are based on a broader review of safety, efficacy, manufacturing, labeling, and risk information.
| Dose | Average weight loss | Average pounds |
|---|---|---|
| 4 mg | about 19.0% | about 47 lbs |
| 9 mg | about 25.9% | about 64 lbs |
| 12 mg | about 28.3% | about 70 lbs |
| Placebo | about 2.2% | about 5 lbs |
In a subgroup with a starting BMI of 35 or higher who continued to 104 weeks (about two years), average weight loss at the 12 mg dose reached about 30.3% (about 85 lbs). At the highest dose, 62.5% of participants lost at least 25% of their body weight, 45.3% lost at least 30%, and 27.2% lost at least 35% over 80 weeks. The trial also reported improvements in waist circumference, non-HDL cholesterol, triglycerides, systolic blood pressure, and an inflammation marker (hsCRP).
These figures come from Eli Lilly's TRIUMPH-1 results. Trial averages describe groups of participants and do not predict how any one person would respond.
What are the side effects of retatrutide?
In TRIUMPH-1, the most common side effects were gastrointestinal and were generally mild to moderate. At the 12 mg dose, compared with placebo, reported rates included nausea (42.4% versus 14.8%), diarrhea (32.0% versus 13.5%), constipation (26.1% versus 10.9%), and vomiting (25.3% versus 4.8%). About 11.3% of participants on the 12 mg dose stopped the medication because of side effects, compared with 4.9% on placebo. Some participants also reported skin sensation changes (dysesthesia) and urinary tract infections. As with any medication, the full safety picture will be clarified as more data are published and reviewed by the FDA. Because retatrutide is investigational, the full safety profile, warnings, contraindications, drug interactions, dosing recommendations, and monitoring guidance will not be known unless and until FDA review and approval occur.
Why retatrutide trial results should not be directly compared with Wegovy or Zepbound
Retatrutide has not been approved and has not been studied head-to-head against Wegovy or Zepbound, so it cannot be directly compared to them yet. What we can do is report what each medication's own clinical trials found, in separate studies with different designs, durations, and participants. These numbers are not interchangeable, and a higher number in one trial does not prove one drug is better than another.
| Medication | Status | Average weight loss reported | Trial |
|---|---|---|---|
| Wegovy (semaglutide 2.4 mg) | FDA-approved, available now | about 15% at 68 weeks | STEP 1 |
| Zepbound (tirzepatide, top dose) | FDA-approved, available now | up to about 21% at 72 weeks | SURMOUNT-1 |
| Retatrutide (12 mg) | Investigational, not approved | about 28% at 80 weeks | TRIUMPH-1 |
The most important column is status. Wegovy and Zepbound are available to patients now. Retatrutide is not. For most people asking this question today, the practical decision is which approved option fits them, not whether to wait for one that is not yet available.
Because retatrutide is investigational and not FDA-approved, its final labeling, dosing, safety warnings, patient eligibility, real-world effectiveness, price, and insurance coverage are unknown.
Is retatrutide FDA-approved? Can I get it now?
No. Retatrutide is investigational and is not FDA-approved. Per Lilly, it is currently available only to people enrolled in its clinical trials. No regulatory submission date or approval timeline has been announced, and additional Phase 3 results (TRIUMPH-2 and TRIUMPH-3) are expected later in 2026. Because it is not approved, no one can confirm its eventual price, insurance coverage, dosing, or which patients will be eligible. Be cautious of any website or seller claiming to offer retatrutide for purchase.
Where retatrutide stands toward FDA approval
- Phase 2 trial completedPublished in the New England Journal of Medicine, 2023.
- Phase 3 TRIUMPH-1 results reportedAnnounced by Lilly on May 21, 2026.
- Additional Phase 3 results (TRIUMPH-2 and TRIUMPH-3)Expected later in 2026.
- FDA submissionNot yet announced.
- FDA decision and approvalNot yet announced.
- Available by prescriptionNot yet. Retatrutide is currently available only through clinical trials.
What can you do now while retatrutide is still in trials?
For patients seeking care now, FDA-approved weight-loss medications may be considered after an individualized clinical evaluation. These options are not appropriate for everyone and may depend on medical history, contraindications, medication availability, insurance coverage, cost, and patient goals. We offer medically supervised weight management with FDA-approved GLP-1 medications including Wegovy and Zepbound, as part of our medical weight loss program.
Should you wait for retatrutide, or start a treatment now?
Whether to start treatment now or wait for future options depends on a person's medical history, goals, risks, preferences, and available treatment choices. Retatrutide does not have an announced approval or availability date. For patients seeking care now, a clinician can review currently FDA-approved weight-loss options, such as Wegovy and Zepbound, and discuss whether any are appropriate. If you would simply like to follow retatrutide's progress in the meantime, you can join the updates list above.
What we tell patients who ask about retatrutide
Patients ask us about retatrutide almost as soon as a new headline runs, usually some version of "should I wait for the one that gets you to thirty percent?" In many cases, patients choose to discuss currently FDA-approved options rather than waiting for a medication with no approved availability date. Newer options like retatrutide can be revisited if FDA approval, labeling, safety information, pricing, and access become clear. Following the science and waiting indefinitely are not the same thing.
Frequently asked questions
Is retatrutide approved by the FDA?
No. It is investigational and available only through clinical trials at this time.
How much weight did people lose on retatrutide?
In the Phase 3 TRIUMPH-1 trial, the highest dose produced an average of about 28% body-weight loss over 80 weeks, and a subgroup followed for about two years averaged about 30%. Individual results vary and trial averages do not predict any one person's outcome.
How do I get retatrutide, or where can I buy it?
Retatrutide is not available for routine prescribing and should not be purchased online or from peptide, research chemical, gray-market, or non-pharmacy sources. Based on current approval status, use should be limited to authorized clinical trials.
How much will retatrutide cost?
The price is not known and will not be set unless and until it is approved.
Is retatrutide a GLP-1 medication?
It includes GLP-1 activity, but it is broader. It acts on three receptors, GIP, GLP-1, and glucagon, which is why it is called a triple agonist.
Is retatrutide better than Zepbound or Ozempic?
No. There is not enough evidence to make that claim. Retatrutide has not been studied head-to-head against Zepbound, Wegovy, or Ozempic, and it has not been approved by the FDA. Results from separate clinical trials should not be used to conclude that one medication is better, safer, or more appropriate for an individual patient.
Can I buy retatrutide as a research peptide online?
We strongly advise against it. Retatrutide sold as a research peptide or from any non-pharmacy source is unregulated, is not quality-controlled, and is not approved for human use. Purity, dose accuracy, and safety are unknown. The only legitimate way to take retatrutide right now is as a participant in a clinical trial.
When will retatrutide be available?
No FDA approval date or routine prescribing availability date has been announced. Additional clinical trial results and regulatory review would be needed before any approved prescribing information, patient eligibility, pricing, or insurance coverage is known.
Sources
- Eli Lilly and Company. Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial. May 21, 2026. investor.lilly.com
- TRIUMPH-1, ClinicalTrials.gov identifier NCT05929066.
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. New England Journal of Medicine. 2023; 389(6):514–526. doi:10.1056/NEJMoa2301972.
This content is for educational purposes only and does not replace medical advice. Retatrutide is investigational and not FDA-approved, and we do not prescribe or provide it. It is currently available only through clinical trials. Treatment decisions are individualized and discussed during a visit.