Diarrhea on Zepbound (tirzepatide): Week-by-Week Timeline of What to Expect

What the Zepbound label says about timing

The prescribing information gives a pattern rather than a calendar: the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time [1]. The adverse reactions section adds that most patients who stopped Zepbound because of an adverse reaction did so during the first few months of treatment, and that those reactions were gastrointestinal [1].

The escalation schedule sets the calendar

The 2.5 mg starting dose is for treatment initiation and is not approved as a maintenance dose [1]. After 4 weeks at 2.5 mg, the dose increases to 5 mg weekly. Later increases may occur after at least four weeks at the current dose, up to maintenance doses of 5, 10 or 15 mg weekly for weight reduction, or 10 or 15 mg for obstructive sleep apnea [1]. The label ties the majority of GI events to that escalation process [1].

Steady state is reached after four weeks of weekly dosing [1].

The label also states that if a maintenance dose is not tolerated, a lower maintenance dose can be considered [1].

Diarrhea rates at each dose

In the pooled trials, 2,519 adults received Zepbound for up to 72 weeks: 630 received 5 mg, 948 received 10 mg and 941 received 15 mg. Another 958 received placebo [1]. Diarrhea, a category that also includes frequent bowel movements, was reported by 8% on placebo, 19% on 5 mg, 21% on 10 mg and 23% on 15 mg [1]. Gastrointestinal adverse reactions of any kind were reported by 56% at every Zepbound dose, compared with 30% on placebo [1].

Those figures cover the whole trial period and are broken out by dose, not by week.

Severe reactions and stopping treatment

Severe gastrointestinal adverse reactions were reported in 1.7% of patients on 5 mg, 2.5% on 10 mg and 3.1% on 15 mg, versus 1% on placebo [1]. Treatment was stopped 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; stopping for any adverse reaction occurred in 4.8%, 6.3% and 6.7% respectively, versus 3.4% on placebo [1].

The label states that Zepbound is not recommended in patients with severe gastroparesis [1].

What the label says to watch for during escalation

The label describes postmarketing reports of acute kidney injury, in some cases requiring hemodialysis, in patients treated with GLP-1 receptor agonists or Zepbound; most of those events occurred in patients who had gastrointestinal reactions leading to dehydration, such as nausea, vomiting or diarrhea [1]. The label calls for renal-function monitoring when reactions could cause volume depletion, especially when treatment starts or the dose increases [1].