Why do I get diarrhea on my period?
Last updated September 3, 2026.
Prostaglandins that cramp the uterus also speed the bowel - period diarrhea is common and peaks with day-one bleeding. Early NSAIDs block the shared chemistry; month-long or bloody diarrhea needs a workup.
What to do
- Start NSAIDs early - they block prostaglandins, easing cramps and gut effects together.
- Go bland and small on bad days - and cut caffeine and fatty foods.
- Hydrate doubly - loose stools plus bleeding is a fluid-loss double.
- Escalate month-long or bloody diarrhea - IBS and bowel endometriosis hide there.
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