Tirzepatide and semaglutide are the two most discussed incretin peptides, sold under names like Mounjaro and Zepbound (tirzepatide) and Ozempic and Wegovy (semaglutide). Both are FDA-approved and given as once-weekly injections, and the main mechanistic difference is how many receptors each one targets.
Reviewed for accuracy · Last reviewed July 7, 2026The one direct head-to-head is SURPASS-2, a Phase 3 diabetes trial. Over 40 weeks, tirzepatide 5, 10, and 15 mg reduced HbA1c by 2.01, 2.24, and 2.30 percentage points, compared with 1.86 points for semaglutide 1 mg. That is a specific diabetes endpoint at a specific semaglutide dose, not a general statement that one is better for everyone.
Mechanistically, tirzepatide adds the GIP receptor to the GLP-1 target semaglutide uses. Both slow gastric emptying and reduce appetite, and both carry the same class boxed warning for thyroid C-cell tumors.
Practical differences often come down to product, dose, tolerability, and access rather than molecule alone. Which is appropriate is a medical decision, and independently sourced vials of either carry no guarantee of the testing a regulated product does.
This page is an independent educational reference and is not medical advice. Talk to a doctor before starting or adjusting any compound.