What are the side effects of tirzepatide?

In SURMOUNT-3, a phase 3 trial of tirzepatide (checked 23 September 2026), nausea was reported by 39.7% of participants against 14.0% on placebo, with diarrhoea, constipation and vomiting also more frequent. Discontinuation because of adverse events was 10.5% against 2.1%, and in SURMOUNT-1 4.3% to 7.1% against 2.6%.

Primara Labs sells some of the compounds covered here. Every figure on this page links to its source and the date it was checked.

Updated 23 September 2026

SURMOUNT-1

In SURMOUNT-1, discontinuation because of adverse events was 4.3% on 5 mg, 7.1% on 10 mg and 6.2% on 15 mg, against 2.6% on placebo.

SURMOUNT-3

In SURMOUNT-3, discontinuation because of adverse events was 10.5% on maximum tolerated dose (10 or 15 mg), against 2.1% on placebo. The most frequently reported adverse events were nausea in 39.7% on maximum tolerated dose (10 or 15 mg) against 14.0% on placebo, diarrhoea in 31.0% on maximum tolerated dose (10 or 15 mg) against 9.2% on placebo, constipation in 23.0% on maximum tolerated dose (10 or 15 mg) against 6.8% on placebo and vomiting in 18.1% on maximum tolerated dose (10 or 15 mg) against 1.4% on placebo.

The results beside them

In SURMOUNT-3, a phase 3 trial of tirzepatide in adults with BMI of 30 or more, or 27 or more with at least one obesity-related complication (excluding diabetes), who achieved 5.0% or more weight reduction after a 12-week intensive lifestyle intervention (n=579), mean body weight changed by -18.4% on maximum tolerated dose (10 or 15 mg) over 72 weeks, against +2.5% on placebo (treatment-regimen estimand; Wadden TA et al. Nat Med 2023 (SURMOUNT-3)).

In SURMOUNT-4, a phase 3 withdrawal trial (n=670), participants who continued tirzepatide after a 36-week lead-in lost a further 5.5% by week 88, while those switched to placebo regained 14.0%.

Reading these rates

Each figure is the share of participants on an arm who reported the event at least once during the trial, set against the same share on placebo. The difference between the two is the part attributable to the trial treatment; the placebo figure shows how common the event is anyway.

Sources

Where every figure comes from

Jastreboff AM et al. N Engl J Med 2022;387:205-216 · checked 23 September 2026
Wadden TA et al. Nat Med 2023 (SURMOUNT-3) · checked 23 September 2026
Aronne LJ et al. JAMA 2024 (SURMOUNT-4) · checked 23 September 2026

Last reviewed 23 September 2026