Tirzepatide
A first-in-class dual agonist of the GIP and GLP-1 receptors, approved as Mounjaro for type 2 diabetes and as Zepbound for chronic weight management. Its dual mechanism delivers some of the largest weight reductions reported in registrational obesity trials.
Retatrutide
An investigational triple agonist targeting GIP, GLP-1, and glucagon receptors. Phase 2 results reported some of the largest weight reductions yet seen with an incretin-based agent, and a phase 3 program is ongoing.
Mechanism
Tirzepatide engages GIP and GLP-1 receptors. Retatrutide adds the glucagon receptor, hypothesized to contribute energy-expenditure and hepatic effects. Whether the glucagon component adds clinical value beyond tolerability cost is precisely what phase 3 is testing.
Evidence
Tirzepatide carries registrational evidence across SURPASS and SURMOUNT programs and is approved. Retatrutide’s phase 2 reported ~17.5% weight reduction at 24 weeks with continued loss to 48 weeks; phase 3 is ongoing and no approval exists yet.
Safety
Tirzepatide’s labeled profile is established. Retatrutide’s known profile so far is dominated by dose-related GI effects, with long-term questions — including pancreatitis and gallbladder risk — still being characterized.
Status
The cleanest summary: tirzepatide is a medicine with a label; retatrutide is a trial compound with a data cutoff. Anything claiming retatrutide’s "approval" or selling it as medicine is outside the regulated system.
Frequently Asked Questions
Is retatrutide just "stronger tirzepatide"?
No — it is a different receptor profile at an earlier stage. Triple agonism changes both the hypothesized benefits and the risk questions, and those questions are unresolved.
When will retatrutide be approved?
That depends on phase 3 results and regulator review; no date is settled. This page tracks evidence, not predictions.
Evidence tier: Approved medicine · Last reviewed: 2026-09-05 · Sources cited below.