Diarrhoea at night: what to know

Food poisoning, gastroenteritis and giardiasis can cause loose stools at any time, often with cramps, nausea or fever. Food intolerance may follow a particular meal, while coeliac disease can cause ongoing digestive symptoms after gluten exposure. Irritable bowel syndrome can fluctuate with meals and stress. Crohn's disease may cause persistent diarrhoea with pain, fatigue or weight change. An overactive thyroid can speed bowel movements and may also cause heat intolerance, tremor or a racing heartbeat. Waking from sleep repeatedly because of diarrhoea is a useful detail to tell a clinician.

Keep water or an oral rehydration drink nearby and take small, regular sips. Eat lightly if hungry, choosing plain foods, and avoid alcohol, excess caffeine and anything you know triggers symptoms. Note the timing of meals, stool appearance, pain, fever, travel, new medicines and other household illness. Wash hands with soap and water after using the toilet. Do not severely restrict food for several days or remove gluten before discussing testing for coeliac disease, because this can affect assessment.

Get urgent help for blood or black stool, severe abdominal pain, fainting, confusion, repeated vomiting, very little urine or inability to drink. Seek medical advice soon when night diarrhoea keeps returning, lasts beyond an acute illness, causes marked tiredness, or comes with fever, weight loss or symptoms of dehydration. A clinician may review medicines, examine you and decide whether stool or blood tests are appropriate.

Ask what pattern your symptoms suggest, whether testing is needed, how to replace fluids, and which medicines should be paused or avoided.