Diarrhoea on your period: causes and relief

Chemical messengers released around menstruation can affect the bowel as well as the uterus, making stools looser or bowel movements more frequent. Cramping, bloating, and changes in appetite may occur at the same time. A stomach infection, food poisoning, food intolerance, coeliac disease, Crohn's disease, irritable bowel syndrome, or an overactive thyroid can produce similar symptoms. A repeated cycle pattern supports a period-related trigger, but it does not rule out another cause.

Drink regularly and replace salts with an oral rehydration solution if stools are frequent. Eat smaller meals and choose foods you already tolerate; limit alcohol, rich foods, and anything that has triggered symptoms before. Gentle warmth may ease cramps. Keep a diary of cycle dates, stool changes, pain, foods, and medicines so a clinician can see whether the pattern is consistent. Check with a pharmacist before using an antidiarrhoeal product.

Get urgent help for fainting, confusion, severe dehydration, severe or one-sided abdominal pain, repeated vomiting, blood or black stool, or a high fever. Book an assessment if diarrhoea occurs outside your period, is becoming more severe, disrupts daily life, or comes with weight change, persistent fatigue, or unusual bleeding. These features can point away from a simple cycle-related change.

Ask whether your timing and other symptoms fit a menstrual bowel pattern, whether another condition should be checked, and which relief options suit your medicines and health history.