What researchers study
Retatrutide is an investigational single-molecule agonist of the GLP-1, GIP and glucagon receptors. It is being studied in late-stage clinical trials for obesity and related metabolic conditions.
Important: Clinical evidence for an FDA-approved or clinical-trial drug does not establish that an online research product with the same ingredient name is equivalent.
Potential side effects & unknowns
Clinical trials have commonly reported gastrointestinal adverse effects such as nausea, diarrhea and constipation. Retatrutide remains investigational, so its final approved labeling, contraindications and long-term safety profile have not been established.
Evidence snapshot
Phase 3 results reported in 2026 showed substantial average weight loss in several study populations. Those results concern Lilly's clinical-trial drug; they do not establish the identity, purity, safety or efficacy of products sold online as 'retatrutide.'