Retatrutide FAQ

Retatrutide, also known as LY3437943, is an investigational once-weekly injection developed by Eli Lilly. It activates GIP, GLP-1 and glucagon receptors and is being studied for obesity, type 2 diabetes and related metabolic conditions.

No. As of September 19, 2026, retatrutide is investigational and has not been approved by the U.S. Food and Drug Administration or any other regulatory agency. Lilly says it is legally available only to participants in its clinical trials.

There is no confirmed public launch date. Lilly said it planned to submit a biologics license application to the FDA in the first quarter of 2027, but a planned submission is not an approval and review timing or outcome cannot be guaranteed.

In the peer-reviewed Phase 2 obesity trial, the 12 mg group lost 24.2% of baseline body weight on average at 48 weeks, compared with 2.1% for placebo. The TRIUMPH-1 sponsor announcement later reported a 28.3% average reduction at 80 weeks for 12 mg in the efficacy estimate, compared with 2.2% for placebo. That Phase 3 figure was company-reported topline data at this review, not yet a full peer-reviewed paper.

These are group averages from controlled trials—not promises for an individual.

That has not been proven by a completed direct comparison. Results from separate trials use different populations, durations, doses and statistical methods, so comparing headline percentages can mislead. The TRIUMPH-5 head-to-head trial of retatrutide versus tirzepatide is ongoing.

The most common trial adverse events have been gastrointestinal, including nausea, diarrhea, constipation and vomiting. They were generally mild to moderate and more frequent at higher doses. Phase 3 announcements also identified dysesthesia, or unusual skin sensations, as a dose-related tolerability issue.

There is no final prescribing label, so the complete long-term safety profile, warnings and contraindications are not established. Read the full safety review.

There is no FDA-approved retatrutide product to prescribe in the United States. Eligible participants may receive the investigational medicine through an authorized clinical trial under that study's protocol.

No product sold online or by a clinic should be assumed to be the same as Lilly's clinical-trial medicine. Because retatrutide is not approved, there is no approved commercial product or standard public prescription supply. Products marketed as compounded, research-grade, “Reta,” “R-10” or “R-20” may have uncertain identity, strength, sterility and purity.

No. “GLP-3” is an informal media or marketing nickname, not the name of a hormone or accepted drug class. Retatrutide is a triple receptor agonist that activates GIP, GLP-1 and glucagon receptors.

Search ClinicalTrials.gov for retatrutide or LY3437943, review the recruitment status and contact the study location listed on the registry. Eligibility depends on the protocol and screening; no third party can guarantee enrollment or charge for a place in a legitimate trial.

The price and insurance coverage are unknown because retatrutide is not approved or commercially available. Any current online price is for an unapproved product, not an authorized retail version of Lilly's medicine.