The most common questions about retatrutide — from availability and dosing to cost and eligibility.
Retatrutide (LY3437943) is an investigational once-weekly injectable drug developed by Eli Lilly and Company. It is a triple receptor agonist — meaning it activates three hormone receptors simultaneously: GLP-1, GIP, and glucagon. This distinguishes it from currently approved drugs like semaglutide (Ozempic/Wegovy), which only targets GLP-1, and tirzepatide (Mounjaro/Zepbound), which targets GLP-1 and GIP.
No. As of 2025, retatrutide is not approved by the FDA or any other regulatory authority. It is currently in Phase 3 clinical trials. If trial results are positive and Eli Lilly submits a New Drug Application (NDA), FDA approval could potentially occur in 2026 or 2027 — but approval is never guaranteed.
Retatrutide is developed by Eli Lilly and Company, a pharmaceutical company headquartered in Indianapolis, Indiana. Eli Lilly also manufactures tirzepatide (Mounjaro and Zepbound) and has been a leading player in the incretin drug space for many years.
The key differences are in the number of receptors targeted and the degree of weight loss observed in trials:
Ozempic / Wegovy (semaglutide) — GLP-1 receptor agonist only. Average weight loss of approximately 15% over 68 weeks in clinical trials.
Mounjaro / Zepbound (tirzepatide) — GLP-1 and GIP dual agonist. Average weight loss of approximately 20–22%.
Retatrutide — GLP-1, GIP, and glucagon triple agonist. Phase 2 data showed average weight loss of approximately 24% at the highest dose over 48 weeks. The glucagon receptor activation is thought to increase energy expenditure and liver fat clearance beyond what dual agonists can achieve.
No. Retatrutide is not available to the general public. The only way to access it currently is through participation in one of Eli Lilly's ongoing clinical trials. You can search for open trials at ClinicalTrials.gov using the search term "retatrutide" or "LY3437943". Eligibility criteria vary by trial.
This depends on the outcome of ongoing Phase 3 trials and regulatory review timelines. If Phase 3 data is positive and Eli Lilly files an NDA with the FDA, approval could realistically come in 2026 or 2027. However, regulatory timelines can shift, and there is always a possibility that additional data may be requested or that trial results could differ from Phase 2 expectations.
Visit ClinicalTrials.gov and search for "retatrutide." Review the eligibility criteria for each study carefully — trials typically have specific requirements around BMI, health conditions, age, and medication history. If you appear eligible, contact the trial site directly to inquire about enrollment. Your primary care physician may also be able to assist with referrals.
Retatrutide is administered as a once-weekly subcutaneous (under-the-skin) injection, similar to semaglutide and tirzepatide. In Phase 2 trials, it was injected into the abdomen, thigh, or upper arm. The drug would likely come in a pre-filled pen injector if it reaches market, but the final commercial formulation has not been confirmed.
In the Phase 2 obesity trial, participants were randomized to receive retatrutide at doses of 1 mg, 4 mg, 8 mg, or 12 mg weekly, or placebo. Doses were typically titrated (gradually increased) over several weeks to reduce gastrointestinal side effects. The highest dose (12 mg) produced the greatest weight loss (average 24.2% over 48 weeks).
Based on Phase 2 trial data, the most commonly reported side effects were gastrointestinal in nature, including nausea, vomiting, diarrhea, constipation, and decreased appetite. These were more frequent at higher doses and during dose escalation periods. Most participants who experienced these effects reported they were mild to moderate and transient. See our full side effects page for more detail.
Yes — as with other GLP-1 receptor agonists, a modest increase in resting heart rate was observed in some participants in Phase 2 trials. This is a known class effect and is typically small in magnitude. Eli Lilly's Phase 3 program will include cardiovascular outcomes monitoring, which will provide more definitive safety data in this area.
Based on Phase 2 data, retatrutide's overall safety profile was considered acceptable by trial investigators, with side effects broadly consistent with the GLP-1 drug class. However, Phase 3 trials involving thousands of participants over longer periods are required to fully characterize long-term safety. No drug should be considered definitively "safe" until it has completed large-scale trials and regulatory review. We are not in a position to make safety claims about an unapproved investigational drug.
No pricing has been announced, as the drug is not yet approved. For reference, semaglutide (Wegovy) has a list price of approximately $1,300–$1,400/month in the US without insurance, and tirzepatide (Zepbound) is priced similarly. It is reasonable to expect retatrutide to be priced in a similar range, though actual pricing will depend on Eli Lilly's commercial strategy and competitive dynamics at the time of launch.
Coverage is entirely unknown at this time, as the drug has not been approved. Insurance coverage for obesity medications varies widely by plan and insurer. If retatrutide is approved, coverage decisions will be made by individual insurers and pharmacy benefit managers based on cost-effectiveness data, clinical guidelines, and negotiations with Eli Lilly.