Tirzepatide
Mounjaro · Zepbound
GIP and GLP-1 receptor agonist (dual agonist)
A once-weekly dual GIP/GLP-1 receptor agonist for type 2 diabetes and chronic weight management.
- Approved for
-
- Type 2 diabetes (Mounjaro)
- Chronic weight management in adults with obesity or overweight with a related condition (Zepbound)
- Titration
- Started at a low weekly dose and increased in steps, generally no sooner than every 4 weeks, to improve gastrointestinal tolerability. Follow the prescribing information and your clinician.
- Common side effects
-
- Nausea
- Diarrhea
- Decreased appetite
- Vomiting
- Constipation
Tirzepatide is a once-weekly injectable that activates two incretin receptors — GIP and GLP-1 — which is why it is called a dual agonist. It is sold as Mounjaro for type 2 diabetes and Zepbound for chronic weight management.
How it works
By engaging both the GIP and GLP-1 receptors, tirzepatide enhances glucose-dependent insulin release, lowers glucagon, slows gastric emptying, and reduces appetite (Zepbound label).
What the evidence shows
In SURMOUNT-1, adults with obesity taking the highest tirzepatide dose lost around 21% of body weight over 72 weeks, compared with about 3% on placebo (SURMOUNT-1, NEJM). In type 2 diabetes, SURPASS-2 showed strong reductions in A1c versus semaglutide 1 mg (SURPASS-2, NEJM).
Side effects and cautions
Gastrointestinal effects — nausea, diarrhea, and reduced appetite — are the most common and usually improve over time. Like other drugs in the class, it carries a boxed warning regarding thyroid C-cell tumors and is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. Review your history with your clinician.