Retatrutide is an investigational drug being studied by Eli Lilly. The FDA has not approved it for any use, its safety and effectiveness have not been established, and it is not available from any pharmacy or compounding facility.
Retatrutide (research designation LY3437943) is an investigational drug being developed by Eli Lilly. "Investigational" is a regulatory status, not a marketing description: it means the drug may be used only in clinical research conducted under an FDA Investigational New Drug application, and that its safety and effectiveness have not been established for any use.
Because it is investigational, retatrutide cannot lawfully be prescribed, sold, or compounded. No pharmacy, 503A or 503B compounding facility, or online retailer may supply it. Weight Method does not offer retatrutide and cannot obtain it.
This page describes what the drug is and where it sits in the regulatory process. It is not a description of what retatrutide does for patients, because that has not been established.
"Triple agonist" is a description of molecular design, not of results. It means a single molecule is built to bind three receptor types rather than one or two. In retatrutide's case those are the GLP-1, GIP, and glucagon receptors.
Those three receptors are part of normal human metabolism and have been studied for decades independently of any particular drug. GLP-1 receptor signaling participates in appetite regulation, in the rate at which the stomach empties, and in glucose-dependent insulin release. GIP receptor signaling participates in the insulin response to food and in how fat tissue handles nutrients. Glucagon receptor signaling participates in the liver's handling of glucose and fat, and in energy expenditure.
Naming the receptors a molecule binds says nothing about whether the resulting drug is safe or whether it works. Whether binding all three produces a clinical benefit, and at what risk, is the question the clinical trials are being conducted to answer. Until those trials are complete and the FDA has reviewed them, no conclusion is available.
A drug reaches the U.S. market only after clinical testing and an FDA review of the resulting data. Retatrutide has completed earlier-phase studies and is currently in Phase 3 trials conducted by Eli Lilly. Phase 3 is the final stage of clinical testing before a sponsor may submit a New Drug Application.
Eli Lilly has published earlier-phase findings in the peer-reviewed literature. Those findings belong to the research record. They are not a basis for patients or providers to draw conclusions about safety or effectiveness, and this site does not summarize them for that purpose. Investigational trial data is preliminary by definition, which is why further trials and an independent regulatory review are required before anyone may say what a drug does.
Eli Lilly has not announced a submission date, and the FDA has not approved retatrutide for any indication.
There is no lawful commercial supply of retatrutide. Compounding pharmacies may only compound using active ingredients that are permitted under the compounding statutes, which requires FDA approval of the ingredient. Retatrutide has no such approval, so no 503A or 503B facility may lawfully prepare it. There is no legitimate compounded retatrutide product.
Any website, clinic, or overseas seller offering retatrutide for human use is operating outside the law. Products sold that way have not been evaluated by anyone for identity, purity, potency, or sterility. What is actually in the vial is unverified, and for an injectable product that is a meaningful hazard rather than a technicality.
If you are weighing medical weight management options that exist today, that is a conversation to have with a licensed provider who knows your health history.