What it is
Retatrutide is an experimental weekly injection from Eli Lilly that acts on three hormone receptors: GLP-1, GIP and glucagon. It is being tested for obesity, type 2 diabetes and related conditions.
The GLP-1 and GIP parts reduce appetite and help control blood sugar, while the glucagon part may increase the energy the body burns and help clear fat from the liver. Researchers are still learning how these effects balance out over the long term.
US regulatory status
Investigational and not FDA-approved. Phase 3 (TRIUMPH and TRANSCEND) trials reported positive results in 2026 and Lilly has offered limited early access to some patients, but no FDA approval has been granted; anything sold online as retatrutide is not a legitimate approved product.
What the research shows
Phase 2 and phase 3 trials published by Lilly reported large average weight loss and A1C reductions compared with placebo, among the largest seen for any obesity drug so far. These are still early results from the company's trials, and full long-term safety data, including heart outcomes, are not yet available.
How it is given
Weekly subcutaneous injection (in clinical trials)
Commonly reported side effects
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Increased heart rate
- Unusual skin sensations (dysesthesia) reported in some trials
Questions to ask your provider
- Am I a candidate for a retatrutide clinical trial?
- Which approved medicines could help me now while retatrutide is still being studied?
- What are the risks of using products sold online that claim to be retatrutide?