Retatrutide
Reviewed
Short answer
Still being studied. Late-stage study reports show meaningful results in people, but no product is approved and no regulatory review is complete. Still being studied in the United States; no FDA-approved retatrutide product.
The Peptide Field explains research. Its pages are not independently medically reviewed, and they do not diagnose, prescribe, or recommend treatment.
Read the study findingsAlso known as RETA · LY3437943 · triple G agonist · triple hormone agonist
Part of Metabolic peptide medicines
Compared with Tirzepatide
Legal status Is Retatrutide legal? See the status table
Study and product details
What it is
Retatrutide is an investigational molecule that acts on three body-signal receptors: GIP, GLP-1, and glucagon. It is not the same molecule as semaglutide or tirzepatide, and it is not an FDA-approved medicine.
Type of peptide: GIP, GLP-1, and glucagon receptor agonist. This describes what the substance is or how it works. It does not show that it is safe, effective, or approved.
What has been studied?
- Moderate: Useful evidence exists, but important limits remain.
- Limited: Research is too small or incomplete, or does not directly answer this question.
A full phase 2 report and several early phase 3 sponsor reports show meaningful results in people. Full reports for the phase 3 studies and FDA review are not complete.
Human dose-response and adverse-event data exist, but the development program is not complete.
Phase 2 exposure cannot define the full safety profile, rare risks, or long-term benefit-risk balance.
High for controlled clinical-trial material; low for products sold outside those trials.
Products with the same ingredient can differ.
The ingredient name does not tell you everything about a product. Check its other ingredients, its form, how it enters the body, and the use and people covered by the research or approval.
None identified in the United States.
- Investigational obesity and metabolic-disease programs
Have a lab test report (COA) for a product sold under this name? Check what the report shows in 10 questions
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What studies found
In a 48-week phase 2 study, people were assigned to groups by chance. Higher study doses were linked to more weight reduction. Lilly announced early sponsor-reported TRIUMPH-1 results in May 2026. It announced early sponsor-reported TRIUMPH-2 and TRIUMPH-3 results in July 2026. These studies covered specific groups of people with obesity. Some groups had type 2 diabetes or established cardiovascular disease, and some did not.
These announcements are early summaries from the study sponsor. They do not replace full reports checked by other experts or FDA review. Retatrutide is still being studied, and other outcome programs remain active. Current records do not show its long-term balance of possible benefits and harms, rare harms, broad real-world effectiveness, or whether products sold outside clinical trials have the same identity.
Which products do these findings apply to?
A product sold under the same name may not match the product used in trials. Retatrutide is still being studied. A study product made under a study protocol does not prove that products sold online under the same name have the same identity or quality.
Side effects reported in Retatrutide trials
In trials, the most common side effects of retatrutide were stomach and bowel problems. These were nausea, diarrhea, constipation, and vomiting.
These side effects were often more common in the higher dose groups. In the phase 2 obesity trial, most were mild to moderate.
Some people also reported dysesthesia, an unpleasant or unusual feeling on the skin. Most of these cases were mild to moderate and went away during treatment.
Each number is the share of people in a group who reported the problem during the trial. The middle column shows the lowest and highest share across the retatrutide dose groups. Placebo means a shot with no medicine in it.
Phase 3 trials
TRIUMPH-1 Phase 3 · 80 weeks
Adults without diabetes who had obesity, or overweight and at least one health problem linked to weight.
| Reported problem | Retatrutide groups | Placebo |
|---|---|---|
| Nausea | 28.6% to 42.4% | 14.8% |
| Diarrhea | 25.2% to 34.1% | 13.5% |
| Constipation | 23.8% to 26.1% | 10.9% |
| Vomiting | 10.6% to 25.3% | 4.8% |
| Colds and other upper airway infections | 12.2% to 14.2% | 11.6% |
| Dysesthesia (unusual skin feeling) | 5.1% to 12.5% | 0.9% |
| Urinary tract infections | 7.5% to 8.8% | 5.3% |
| Stopped treatment because of side effects | 4.1% to 11.3% | 4.9% |
Source for TRIUMPH-1: Lilly early results , posted . Not yet checked by outside experts.
TRIUMPH-2 Phase 3 · 80 weeks
Adults with type 2 diabetes and obesity or overweight.
| Reported problem | Retatrutide groups | Placebo |
|---|---|---|
| Diarrhea | 27.4% to 33.6% | 13.2% |
| Nausea | 13.7% to 28.0% | 8.0% |
| Constipation | 14.0% to 16.8% | 9.4% |
| Less hunger | 5.8% to 17.1% | 4.5% |
| Vomiting | 5.5% to 15.7% | 4.2% |
| Dysesthesia (unusual skin feeling) | 4.5% to 7.3% | 0.7% |
| Urinary tract infections | 3.8% to 8.0% | 6.6% |
| Stopped treatment because of side effects | 3.8% to 11.6% | 4.9% |
Source for TRIUMPH-2: Lilly early results , posted . Not yet checked by outside experts.
TRIUMPH-3 Phase 3 · 80 weeks
Adults with severe obesity and heart or blood vessel disease, with or without type 2 diabetes.
| Reported problem | Retatrutide groups | Placebo |
|---|---|---|
| Diarrhea | 24.4% to 30.1% | 8.7% |
| Nausea | 21.7% to 22.4% | 5.8% |
| Constipation | 15.7% to 18.0% | 7.1% |
| Less hunger | 13.5% to 14.5% | 3.0% |
| High blood sugar | 3.1% to 3.9% | 13.4% |
| Dysesthesia (unusual skin feeling) | 6.4% | 1.3% |
| Urinary tract infections | 6.1% to 7.0% | 5.3% |
| Stopped treatment because of side effects | 9.8% to 13.5% | 4.8% |
Source for TRIUMPH-3: Lilly early results , posted . Not yet checked by outside experts.
Phase 2 trials and serious side effects
Phase 2 trials
Phase 2 obesity trial (NCT04881760) Phase 2 · 48 weeks
338 adults with obesity, or with overweight and a health problem linked to weight.
| Reported problem | Retatrutide groups | Placebo |
|---|---|---|
| Nausea | 14.5% to 60.0% | 11.4% |
| Diarrhea | 8.7% to 20.0% | 11.4% |
| Constipation | 6.1% to 16.1% | 2.9% |
| Vomiting | 2.9% to 25.7% | 1.4% |
| Less hunger | 11.4% to 31.4% | 8.6% |
| Any serious side effect | 0% to 6.1% | 4.3% |
Source for Phase 2 obesity trial (NCT04881760): ClinicalTrials.gov posted results , posted .
Phase 2 type 2 diabetes trial (NCT04867785) Phase 2 · 36 weeks
281 adults with type 2 diabetes. This trial also had a dulaglutide group, which is not shown.
| Reported problem | Retatrutide groups | Placebo |
|---|---|---|
| Nausea | 4.3% to 41.7% | 4.4% |
| Diarrhea | 2.1% to 29.2% | 4.4% |
| Constipation | 6.4% to 16.7% | 2.2% |
| Vomiting | 0% to 16.7% | 2.2% |
| Less hunger | 4.3% to 20.8% | 0% |
| Any serious side effect | 4.2% to 8.3% | 6.7% |
Source for Phase 2 type 2 diabetes trial (NCT04867785): ClinicalTrials.gov posted results , posted .
Serious side effects in phase 2
The two phase 2 trials gave retatrutide to 457 people and placebo to 115 people. In the retatrutide groups, 3 people had sudden pancreatitis, a swollen and painful pancreas, listed as a serious event. 2 people had gallbladder inflammation listed as a serious event. Neither problem was listed as a serious event in the placebo groups.
These counts are too small to show whether retatrutide caused them. Larger and longer trials are needed to measure rare harms.
Heart rate
In the phase 2 obesity trial, heart rate rose more in the higher dose groups. The rise was largest at 24 weeks and then went down. Phase 2 obesity trial, New England Journal of Medicine, 2023
What these numbers do not show
- The phase 3 numbers are early summaries from Lilly, the company that makes retatrutide. Full reports checked by other experts were not available when this was checked. ClinicalTrials.gov had not posted phase 3 results.
- Trials can miss rare harms and harms that take years to appear.
- These numbers come from the trial medicine. They do not describe products sold online as research retatrutide, which FDA says are unapproved and of unknown quality.
Report a side effect
You can report a suspected side effect to the FDA at 1-800-FDA-1088 or through FDA MedWatch . If a reaction feels serious, get medical care first.
Trial sources checked .
Fact checks
6 statements checked. Read what the results mean.
“Retatrutide caused weight loss in a randomized human trial.”
The phase 2 trial reported dose-dependent weight reduction over 48 weeks in a defined adult population.
- What this answer is based on
- Health results from a study with randomly assigned groups
- Limits of this answer
- Adults meeting the phase 2 obesity-trial criteria over 48 weeks.
Sources for this fact check (1)
“Retatrutide is FDA-approved.”
It remains investigational. FDA says retatrutide is not a component of an approved drug and has not been found safe and effective for any condition. Positive trial results and sponsor announcements are not marketing approval.
- What this answer is based on
- Official record or product label
- Limits of this answer
- United States regulatory status as reviewed August 1, 2026.
Sources for this fact check (1)
“Phase 3 trials showed retatrutide produced average weight reduction above 20%.”
Lilly reported average weight reduction of up to 20.8% in TRIUMPH-2 and up to 22.6% in TRIUMPH-3 at 80 weeks. These are sponsor-reported topline efficacy-estimand figures and group averages, not individual outcomes, and no full peer-reviewed report of either trial was available in the records reviewed here.
- What this answer is based on
- Study results reported by its sponsor
- Limits of this answer
- Adults meeting the TRIUMPH-2 (obesity or overweight with type 2 diabetes) and TRIUMPH-3 (severe obesity with established cardiovascular disease) entry criteria at 80 weeks, as disclosed by Lilly in July 2026.
Sources for this fact check (3)
Show 3 more fact checks
“The TRIUMPH-3 results show retatrutide prevents cardiovascular events.”
TRIUMPH-3 was not a definitive cardiovascular-outcomes trial. The sponsor reported a hazard ratio of 0.82 (95% CI 0.55 to 1.22) for the five-component major adverse cardiovascular event measure and 1.12 (95% CI 0.64 to 1.96) for the three-component measure. Both intervals include 1.0 and are wide, so studying a molecule in people with cardiovascular disease is not the same as showing it prevents events.
- What this answer is based on
- Study results reported by its sponsor
- Limits of this answer
- The TRIUMPH-3 cardiovascular-event analyses as disclosed by Lilly in July 2026, pending a full report.
Sources for this fact check (2)
“Retatrutide is being submitted to FDA, so it will be available in 2027.”
Lilly states it plans to submit retatrutide for obesity in the first quarter of 2027. A planned submission is a future corporate action, not regulatory acceptance, approval, a prescribing label, or a launch date. Until an approval is recorded by the regulator, the accurate U.S. status remains investigational.
- What this answer is based on
- Official record or product label
- Limits of this answer
- The sponsor-stated first-quarter 2027 U.S. submission plan as reviewed August 1, 2026.
Sources for this fact check (2)
“Research retatrutide sold online is the same as clinical-trial material.”
A matching label name does not establish sequence, purity, sterility, formulation, storage, or clinical equivalence. FDA warns that retatrutide products sold directly to consumers as research material are unapproved and of unknown quality.
- What this answer is based on
- No reliable studies showing this health result in people
- Limits of this answer
- Products outside an authorized clinical-development supply chain.
Sources for this fact check (2)
Questions people ask about Retatrutide
In trials, the most common side effects were nausea, diarrhea, constipation, and vomiting. In TRIUMPH-1, Lilly, the company that makes retatrutide, reported nausea in 28.6% to 42.4% of people on retatrutide and 14.8% on placebo. These are early company results. In a phase 2 trial, most stomach and bowel side effects were mild to moderate. Some people also reported dysesthesia, an unpleasant or unusual feeling on the skin. Rare and long-term risks are not known yet.
Risks and safety limits
An investigational molecule is not a self-treatment category. This guide does not provide trial-drug access, sourcing, dosing, injection, or combination instructions.
This editorial review did not determine sport eligibility. Athletes must check the current prohibited list, Global DRO, and their governing body.
Reviewed .Check the rules for athletes ↗Terms used in the studies
- agonist
- a substance that activates a receptor
- phase 2
- a mid-stage study in people that checks effects and safety before larger studies
- sponsor-reported
- a result shared by the organization that sponsors the study; a full report may not be available
- outcome
- what the study measured
- clinical trial
- a planned study in people
- benefit-risk
- a comparison of possible benefits with possible harms for a defined use and group
- randomized
- assigned to study groups by chance
- investigational
- still being studied and not approved for that use
Read the sources
Show 11 sources
Review history
Revalidated FDA approval status, the boundary between trial material and online products, and the distinction between a planned 2027 submission and approval or availability.
Registered the Phase 3 and submission-plan statements as scoped claim records and split the TRIUMPH-1 and TRIUMPH-2/3 disclosure dates. No new evidence was reviewed.
Added Lilly's July 2026 early sponsor-reported Phase 3 results. Rechecked that retatrutide remained under study and not FDA-approved. Also checked the limits for products sold under its name.
Checked against the phase 2 publication and the June 2026 TRIUMPH-1 registry update: study complete, no summary results posted.
Not independently medically reviewed. This page is not a dosing, sourcing, or treatment guide.
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