Medications
What is retatrutide?
An overview of retatrutide — an investigational triple-hormone agonist being studied for obesity and metabolic disease, and why it is not yet available by prescription.
6 min read · Updated 2026-05-27
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Key takeaways
- Retatrutide is an investigational triple agonist (GLP-1 + GIP + glucagon).
- It is in Phase 3 trials and is not FDA-approved.
- Products sold online as ''retatrutide'' are unregulated and not the same as the trial drug.
What retatrutide is
is an developed by Eli Lilly.
It is a : it activates three at once — , , and .
Why three receptors matter
GLP-1 reduces appetite and improves .
GIP appears to amplify GLP-1's effects and may help with fat .
Glucagon, perhaps counterintuitively, can increase when paired with the other two.
Combining all three is the working theory behind why retatrutide has shown larger weight loss in trials than single- or drugs.
Where it is in development
Retatrutide is in clinical trials as of 2024-2025.
results published in the New England Journal of Medicine reported substantial average weight reduction at the highest doses studied.
It is not and is not available by prescription anywhere in the world.
For more on how retatrutide has been dosed in the trial program, see how retatrutide dosing appears in clinical trials.
Why the name keeps appearing online
Vials labeled as retatrutide are being sold by so-called vendors. These products are not regulated as medicines, are not verified for identity or purity, and are not legal to use as drugs.
Coverage of trial results has driven interest well ahead of any approval.
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