Side effects

Diarrhea on GLP-1 medications

Pending medical review

By Joshua Nichvolodoff · Fact-checked against sources November 2, 2026 · Next review due May 1, 2027

Clinical review: not yet reviewed by a clinician. How review works · Editorial policy

Diarrhea is one of the more common stomach side effects with semaglutide and tirzepatide. In trials it was usually short-lived; the thing to watch is losing too much fluid.

How often it was reported

People reporting diarrhea in the trials behind each US label[1][3][4][5]
ItemOn the medicineOn placebo
Wegovy 2.4 mg (weight management)30%16%
Zepbound 5 / 10 / 15 mg (weight management)19% / 21% / 23%8%
Ozempic 0.5 mg / 1 mg (type 2 diabetes)8.5% / 8.8%1.9%
Mounjaro 5–15 mg (type 2 diabetes)12–17%9%
Different trials, populations and doses — compare within a row, not across rows.

How long it lasted in trials

In a pooled analysis of the STEP 1–3 trials, 29.7% reported diarrhea on semaglutide 2.4 mg versus 15.9% on placebo, and the median episode lasted 3 days[2]. In STEP 1, diarrhea was among the most common side effects and was typically short-lived and mild to moderate[6]. These are averages; they can't predict your experience.

Why fluids matter

Acute kidney injury, sometimes needing dialysis, has been reported after approval, mostly in people whose stomach side effects led to dehydration; the Medication Guides say to tell a healthcare provider right away about nausea, vomiting or diarrhea that does not go away, and to drink fluids[1][3]. In Wegovy's trials, low blood pressure and fainting were also more common than on placebo, some related to fluid loss[1].

General information from product labels and published studies — not medical advice.

Sources

  1. WEGOVY (semaglutide) injection and tablets — prescribing information and Medication Guide (revised 06/2026). U.S. Food and Drug Administration, June 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/218316s007lbl.pdf. Accessed November 2, 2026. Back to the text
  2. Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss. Diabetes, Obesity and Metabolism, January 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9293236/ · DOI 10.1111/dom.14551 · PMID 34514682. Accessed November 2, 2026. Back to the text
  3. ZEPBOUND (tirzepatide) injection — prescribing information and Medication Guide (revised 04/2026). U.S. Food and Drug Administration, April 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/217806Orig1s050lbl.pdf. Accessed November 2, 2026. Back to the text
  4. OZEMPIC (semaglutide) injection — prescribing information (revised 05/2026). U.S. Food and Drug Administration, May 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/209637s038lbl.pdf. Accessed November 2, 2026. Back to the text
  5. MOUNJARO (tirzepatide) injection — prescribing information (revised 08/2026). U.S. Food and Drug Administration, August 2026. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/215866s044s045lbl.pdf. Accessed November 2, 2026. Back to the text
  6. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine, March 18, 2021. https://pubmed.ncbi.nlm.nih.gov/33567185/ · DOI 10.1056/NEJMoa2032183 · PMID 33567185. Accessed November 2, 2026. Back to the text

Figures marked “as reported” are historical: they show what the source said on that date, not today's price or rule.

Changes to this page

  • — First published.

Substantive corrections are also logged at corrections.

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