Can metformin cause diarrhea?

Licensed Pharmacist

Updated Oct 28, 2025 • Published Oct 28, 2025

Fact Checked

Digestive system effects can occur in up to 75% of people who take metformin. Diarrhea is more common with the immediate-release form compared to the extended-release form. In clinical trials, diarrhea occurred in 53.2% of people taking immediate-release metformin and in 10% of people taking extended-release metformin.

Sources:

Metformin hydrochloride tablets, Food and Drug Administration (2012)
Metformin hydrochloride extended-release tablets for oral use, Food and Drug Administration (2023)

Written by Ashley Wong, Pharm. D.

Licensed Pharmacist

Ashley Wong, Pharm.D., has worked for healthcare companies where she translated complex drug information into easy-to-understand language for patients. She also served as a Senior Medical Information Specialist at a medical communications company, where she delivered clinically accurate drug information to healthcare providers and patients and compiled adverse event reports in accordance with the FDA's reporting guidelines.

Can metformin cause diarrhea?

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