Compared, cited
Tirzepatide vs Retatrutide
Tirzepatide hits two gut-hormone receptors and is FDA-approved. Retatrutide hits three and is still in trials. The Phase 2 numbers for retatrutide are large - so is the gap in how far along the evidence is.
Last updated August 2026
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| At a glance | Tirzepatide | Retatrutide |
|---|---|---|
| Receptors | GLP-1 + GIP (dual) | GLP-1 + GIP + glucagon (triple) |
| Status | FDA-approved (Mounjaro, Zepbound) | Investigational; Phase 3 ongoing |
| Half-life | ~5 days | ~6 days |
| Best trial weight loss | -20.9% average (SURMOUNT-1, 15 mg, 72 wk) | -24.2% average (Phase 2, 12 mg, 48 wk) |
| Availability | Prescribable | Not available; clinical trials only |
Two receptors versus three
Tirzepatide adds GIP to GLP-1. Retatrutide adds a third target, the glucagon receptor, on top of both. Activating glucagon may raise energy expenditure, which is the leading theory for retatrutide's larger average weight loss in its Phase 2 trial.
Approved versus investigational
This is the decisive difference. Tirzepatide is FDA-approved, prescribable, and supported by large Phase 3 trials with an established safety profile. Retatrutide is not approved for anything - its Phase 3 program (TRIUMPH) is ongoing, its long-term safety is still being established, and there is no approved dose. Any retatrutide sold outside a trial is unapproved.
What the numbers show, and do not
Retatrutide's -24.2% is from a Phase 2 trial of 338 people over 48 weeks; tirzepatide's -20.9% is from a large Phase 3 trial. These are different trials of different sizes and lengths, not a head-to-head, so the gap is suggestive, not settled. Both are averages, and individual results vary.
Who fits which
Tirzepatide
Available now, FDA-approved, with the larger and more mature evidence base.
Retatrutide
Only inside clinical trials. Promising Phase 2 data, but unproven long-term and not a legal approved drug.
The cited card
Tirzepatide
GLP-1 / GIP dual agonist
The cited card
Retatrutide
GLP-1 / GIP / glucagon triple agonist
Questions people ask
Is retatrutide better than tirzepatide?
Retatrutide produced more average weight loss in its Phase 2 trial (about 24% vs tirzepatide's roughly 21% in a separate Phase 3 trial), but this is not a head-to-head comparison, retatrutide is investigational, and it is not FDA-approved. This is educational information, not medical advice.
Can I get retatrutide?
Not as an approved medication. Retatrutide is still in clinical trials and has no FDA approval, so it is not legally available as a prescribed drug.
Sources
- [1]Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), NEJM 2022Tirzepatide 15 mg: -20.9% mean weight change at 72 weeks.
- [2]Triple-Hormone-Receptor Agonist Retatrutide for Obesity, Phase 2, NEJM 2023Retatrutide 12 mg: -24.2% mean weight loss at 48 weeks vs -2.1% placebo.
Full cited data for each compound is on its library page, linked above. Weight-loss figures are trial averages; individual results vary.
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