Retatrutide vs Tirzepatide
An investigational triple agonist versus the approved dual agonist.
Retatrutide (triple GLP-1/GIP/glucagon agonist)
An investigational once-weekly triple receptor agonist producing the largest pharmacological weight loss reported to date in trials.
Tirzepatide (dual GIP/GLP-1 receptor agonist)
A first-in-class dual GIP and GLP-1 receptor agonist with superior weight loss and glycemic control versus GLP-1 mono-agonists.
| Attribute | Retatrutide | Tirzepatide |
|---|---|---|
| Category | Metabolic | Metabolic |
| FDA status | Investigational, not FDA-approved; Phase 3 TRIUMPH-1 reported May 2026; submission expected late 2026 | FDA-approved (Mounjaro for T2D and, from August 2026, to reduce major cardiovascular events in T2D; Zepbound for weight management and sleep apnea) |
| Half-life | ~6 days | ~5 days |
| Molecular weight | ~4,731 Da | 4,813.5 Da |
| Mechanism | Agonizes GLP-1, GIP, and glucagon receptors. The added glucagon activity increases energy expenditure and hepatic fat oxidation, complementing the appetite and insulin effects of the incretin receptors. | Simultaneously activates GIP and GLP-1 receptors, enhancing glucose-dependent insulin secretion, reducing glucagon, delaying gastric emptying, and reducing appetite. The GIP component is thought to add complementary metabolic effects. |
| Legal status (US) | Investigational, not approved for any indication | FDA-approved, prescription only |
Frequently asked questions
What is the difference between Retatrutide and Tirzepatide?
Retatrutide: An investigational once-weekly triple receptor agonist producing the largest pharmacological weight loss reported to date in trials. Tirzepatide: A first-in-class dual GIP and GLP-1 receptor agonist with superior weight loss and glycemic control versus GLP-1 mono-agonists.
Which has stronger research evidence, Retatrutide or Tirzepatide?
Retatrutide is rated Moderate and Tirzepatide is rated Strong for evidence level in this database. Evidence level reflects the quality of published research, not a recommendation.
Are Retatrutide and Tirzepatide FDA-approved?
Retatrutide: Investigational, not FDA-approved; Phase 3 TRIUMPH-1 reported May 2026; submission expected late 2026. Tirzepatide: FDA-approved (Mounjaro for T2D and, from August 2026, to reduce major cardiovascular events in T2D; Zepbound for weight management and sleep apnea).
Evidence levels reflect the quality of published research, not a recommendation. This comparison is educational and is not medical advice.