What the studies show
Nausea, diarrhoea and vomiting, mostly during dose escalation. In SURMOUNT-5, GI-related discontinuation was 2.7% vs 5.6% on semaglutide.
“The most common adverse events with tirzepatide were gastrointestinal, and most were mild to moderate in severity, occurring primarily during dose escalation.”
Several well-run randomised trials in people, pointing the same way. You can plan around this. It still says nothing about whether the effect is worth the side effects for you.
- 1Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1).N Engl J Med, 2022;387:205–2162,539 adults; −20.9% at 72 weeks on 15 mg.
- 2Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5).N Engl J Med, 2025;393(1):26–36751 adults, 72 weeks; −20.2% vs −13.7%; waist −18.4 cm vs −13.0 cm.
In context
Tirzepatide is a once-weekly peptide that activates both GIP and GLP-1 receptors. It is approved for type 2 diabetes, weight management and obstructive sleep apnoea, and since August 2026 in the US to lower the risk of major cardiovascular events in adults with type 2 diabetes at high risk. In the only direct head-to-head trial it produced more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks) with a similar side-effect profile. It is a prescription medicine; versions sold outside that channel are unlicensed.
Tirzepatide is approved (rx). Legal status differs by country — see the regulation section or the jurisdiction pages.
Questions
Is Tirzepatide proven to cause GI side effects?
What studies are behind the grade?
Is Tirzepatide approved for this?
Other outcomes for Tirzepatide
- ABody weight10+ RCTs
- ABlood glucose (HbA1c)5 SURPASS RCTs
- AObstructive sleep apnoea2 RCTs
- ACardiovascular events1 large outcomes RCT (n=13,165)
Written and maintained by LYO Research — how pages are written and checked. Reviewed 7 October 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →