Diarrhea on Zepbound (Tirzepatide): Incidence, Severity, and Realistic Expectations

How common is diarrhea on Zepbound?

The Zepbound label pools two placebo-controlled weight-management trials, SURMOUNT-1 and SURMOUNT-2, in adults with obesity or overweight, with or without type 2 diabetes, running up to 72 weeks with a 4-week off-drug follow-up [1]. In that pool, 2,519 adults received Zepbound [1]. Diarrhea was reported by 19% of patients on 5 mg (n=630), 21% on 10 mg (n=948) and 23% on 15 mg (n=941), compared with 8% of the 958 patients on placebo [1]. The label's diarrhea category includes both diarrhea and frequent bowel movements [1].

The gap between the treated groups and placebo is 11 to 15 percentage points [1].

For class context, a 2024 review of obesity medications in JAMA lists diarrhea among the adverse effects of the nutrient-stimulated hormone drugs liraglutide, semaglutide and tirzepatide, at 21% to 30% [3].

Is diarrhea worse at higher doses?

The label's diarrhea rates rise with dose: 19%, 21% and 23% at 5 mg, 10 mg and 15 mg, against 8% on placebo [1]. The label's table gives rates for 5, 10 and 15 mg; 2.5 mg is a starting dose and is not approved as a maintenance dose [1].

The same direction shows up in the label's severity figures. Severe gastrointestinal reactions as a group were 1.7% at 5 mg, 2.5% at 10 mg and 3.1% at 15 mg, versus 1% on placebo, with similar rates reported in the label's trials for obstructive sleep apnea [1].

How severe is the diarrhea?

The label reports severe gastrointestinal adverse reactions collectively rather than by individual symptom, so its 1.7% to 3.1% figure covers nausea, vomiting, diarrhea and the rest as one category rather than diarrhea alone [1].

A head-to-head trial offers a direct description of severity. SURMOUNT-5 was an open-label trial of 751 adults with obesity and no type 2 diabetes, comparing maximum tolerated tirzepatide (10 or 15 mg) with maximum tolerated semaglutide (1.7 or 2.4 mg) over 72 weeks [2]. The investigators reported that the most common adverse events in both groups were gastrointestinal and that most were mild to moderate in severity [2].

How often does diarrhea lead people to stop Zepbound?

The label reports discontinuation for gastrointestinal adverse reactions as a group: 1.9% at 5 mg, 3.3% at 10 mg and 4.3% at 15 mg, versus 0.5% on placebo [1]. Any gastrointestinal adverse reaction was reported by 56% of patients on every Zepbound dose, versus 30% on placebo [1].

The label also gives discontinuation for any adverse reaction: 4.8% at 5 mg, 6.3% at 10 mg and 6.7% at 15 mg, versus 3.4% on placebo [1]. It states that the majority of patients who discontinued Zepbound for adverse reactions did so during the first few months, for gastrointestinal reactions [1].

When does diarrhea start?

The labeled schedule starts at 2.5 mg once weekly for 4 weeks, then increases to 5 mg, with further 2.5 mg steps after at least 4 weeks on the current dose [1]. The label states that the escalation schedule is used to reduce the risk of gastrointestinal adverse reactions, and that most nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time [1].

A 2025 review of GLP-1-based obesity therapies notes that their adverse events are primarily gastrointestinal, including nausea, vomiting, obstipation or diarrhea, which often can be mitigated by slow up-titration [4].

If a maintenance dose is not tolerated, the label says to consider a lower maintenance dose [1].

How does it compare with semaglutide?

SURPASS-2 compared tirzepatide 5, 10 and 15 mg with semaglutide 1 mg over 40 weeks in 1,879 adults with type 2 diabetes on metformin [5]. Diarrhea occurred in 13% to 16% of tirzepatide-treated patients versus 12% of those on semaglutide 1 mg [5]. Those figures come from a trial in type 2 diabetes and do not establish how Zepbound's diarrhea rate compares with semaglutide in the weight-management population [5].

A meta-analysis of 10 randomized trials covering 9,873 patients found that diarrhea and other gastrointestinal adverse events were more frequent with tirzepatide than with placebo or basal insulin, but similar to GLP-1 receptor agonists [6]. A 2025 network meta-analysis of 39 studies covering 33,354 people with overweight or obesity and no diabetes found that nausea, vomiting, diarrhea and constipation were the most common gastrointestinal adverse events across this drug class [7].

What does the label say to watch for?

The label warns about acute kidney injury from volume depletion. Postmarketing reports describe acute kidney injury, in some cases requiring hemodialysis, and the majority of reported events occurred in patients who had gastrointestinal reactions leading to dehydration, such as nausea, vomiting or diarrhea [1]. It says to monitor renal function in patients reporting reactions that could lead to volume depletion, especially during initiation and escalation of Zepbound [1].

The label also lists severe gastrointestinal adverse reactions as a warning and states that Zepbound is not recommended in patients with severe gastroparesis [1].