Zepbound (Tirzepatide) Diarrhea: The Biology of Why It Happens and How to Manage It

How common is diarrhea with Zepbound?

The Zepbound label pools two placebo-controlled weight-management trials, SURMOUNT-1 and SURMOUNT-2, with 958 patients on placebo and 630, 948, and 941 patients on 5 mg, 10 mg, and 15 mg, respectively; treatment lasted up to 72 weeks [1]. Diarrhea was reported by 8% on placebo, 19% on 5 mg, 21% on 10 mg, and 23% on 15 mg [1]. The label counts diarrhea and frequent bowel movements together under the diarrhea term [1]. Any gastrointestinal adverse reaction occurred in 56% of patients on every Zepbound dose versus 30% on placebo [1]. Treatment was discontinued for a gastrointestinal adverse reaction by 1.9% on 5 mg, 3.3% on 10 mg, and 4.3% on 15 mg, versus 0.5% on placebo [1].

Severe gastrointestinal reactions were less common but rose with dose: 1.7% on 5 mg, 2.5% on 10 mg, and 3.1% on 15 mg, versus 1% on placebo [1]. The label says Zepbound is not recommended in patients with severe gastroparesis [1].

A 2024 review in JAMA of obesity medications put diarrhea at 21% to 30% across the nutrient-stimulated hormone-based drugs, a group that includes tirzepatide [2].

Why does Zepbound cause diarrhea?

Tirzepatide activates both GIP and GLP-1 receptors [1]. Zepbound delays gastric emptying, with the largest effect after the first dose [1]. Separately, most nausea, vomiting and diarrhea occurred during dose escalation and decreased over time [1].

The label lists diarrhea as a common adverse reaction and separately states that Zepbound delays gastric emptying, but it does not say how much that delay contributes to diarrhea [1].

What does the label say about dose escalation?

The recommended starting dose is 2.5 mg once weekly for 4 weeks [1]. After that, the dose is 5 mg once weekly; further increases are 2.5 mg steps after at least 4 weeks on the current dose, with maintenance doses of 5, 10, or 15 mg for weight reduction and 10 or 15 mg for OSA [1]. The label says the escalation schedule is followed to reduce the risk of gastrointestinal adverse reactions [1]. If a patient does not tolerate a maintenance dose, the label says to consider a lower maintenance dose [1].

What are the safety concerns with diarrhea?

The label warns about acute kidney injury from volume depletion [1]. Most reported kidney injury events occurred in patients who had gastrointestinal adverse reactions leading to dehydration, such as nausea, vomiting, or diarrhea [1]. The label 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 acute pancreatitis among warnings [1]. It says to observe patients for persistent or severe abdominal pain, sometimes radiating to the back, which may or may not be accompanied by nausea or vomiting, and to discontinue Zepbound if pancreatitis is suspected [1].

Does the label name a diarrhea medicine?

No. The Zepbound label names no antidiarrheal medicine. Its drug-specific steps for gastrointestinal reactions are the dose-escalation schedule and the option of a lower maintenance dose when a maintenance dose is not tolerated [1].

Does diarrhea get better over time?

The label says most nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time [1]. In the pooled trials, diarrhea was more frequent at higher doses: 19% on 5 mg, 21% on 10 mg, and 23% on 15 mg, versus 8% on placebo [1].