Why do I get diarrhea on my period?

Period diarrhea is the same chemistry as period cramps, one organ over. Prostaglandins - the chemicals that make the uterus contract to shed its lining - do not stay neatly in the uterus; they circulate to the bowel next door and speed its contractions too. Faster transit means looser, more frequent stools, typically worst on the first day or two of bleeding when prostaglandin levels peak. It is extremely common - studies suggest a large share of women get gut symptoms with their period - and it is the same reason cramps and diarrhea so often arrive together. What helps: NSAIDs like ibuprofen started just before or at the first sign of the period - they block prostaglandin production, which is why they ease cramps and the bowel effects together; smaller, blander meals on the worst days; limiting caffeine and fatty foods, which speed the gut independently; and hydration, since loose stools plus bleeding is a fluid-loss double. Heat on the belly helps the cramp side. When it is more than the period: diarrhea that persists all month, comes with blood, weight loss, or severe pain between periods, or bowel symptoms that track the cycle but are disabling - that pattern can mark IBS, endometriosis involving the bowel, or other gut conditions, and it deserves a proper evaluation. Pymander is a free AI doctor, 24/7 by text. Describe the timing and severity, and it can help you manage or escalate.