Semaglutide vs. tirzepatide: how we choose
Medically reviewed by Alicia Jimenez, APRN · November 2026
Both are weekly injections that reduce appetite. Semaglutide acts on one gut hormone receptor (GLP-1); tirzepatide acts on two (GLP-1 and GIP). In studies, tirzepatide produced more weight loss on average, but the right choice depends on your history, side effects and budget.
What the studies show
In the STEP 1 trial, adults on semaglutide 2.4 mg lost 14.9% of body weight on average over 68 weeks. In SURMOUNT-1, adults on tirzepatide 15 mg lost 20.9% over 72 weeks. In a 2025 head-to-head trial (SURMOUNT-5), tirzepatide averaged 20.2% vs. 13.7% for semaglutide. These trials used brand-name medication alongside diet and exercise.
Side effects
Both commonly cause nausea, constipation or diarrhea, especially as the dose rises. Starting low and increasing slowly helps. Neither is for people with a personal or family history of medullary thyroid cancer or MEN2, or who are pregnant.
How Alicia decides
She looks at your labs, other medications, past results with either drug and how you tolerate side effects. Many people start on semaglutide; tirzepatide is often an option after a plateau. Cost matters too, since tirzepatide usually costs more.
What stays the same
Whichever you take, the program includes monthly check-ins, InBody scans to protect muscle, and nutrition coaching so results last after the dose comes down.
Individual results vary. This article is general information, not medical advice. Book a consultation to talk about your situation.