Crohn's disease and diarrhoea: what to know

Diarrhoea is a common presentation of Crohn's disease and may reflect inflammation in the bowel, an active flare, infection, or another digestive problem; ongoing symptoms need medical assessment. Crohn's disease can affect different parts of the digestive tract, so bowel changes may occur with cramps, abdominal pain, urgency, tiredness, reduced appetite, or weight loss.

Inflammation can make the bowel move contents quickly and can reduce the time available to absorb water. If the small bowel is affected, digestion and absorption may also be disrupted. Blood or mucus, night-time bowel movements, fever, worsening cramps, or a marked change from your usual pattern can suggest more active inflammation, although these features can have other causes. Medicines, recent antibiotics, food intolerance, and stomach infections may also trigger diarrhoea in someone who has Crohn's disease.

A symptom diary can help show whether diarrhoea follows meals, occurs during the night, comes with pain or urgency, or changes after a medicine. Record stool appearance, any blood, fluid intake, temperature, and other symptoms without stopping prescribed treatment on your own.

Arrange a GP consultation if diarrhoea continues, keeps returning, or is affecting daily activities. Take your medicine list and symptom diary, and mention recent travel, antibiotics, sick contacts, dietary changes, or a previous Crohn's flare. Drink fluids regularly; a pharmacist or clinician can advise whether an oral rehydration drink is suitable. Choose foods you tolerate and avoid making major restrictive diet changes without professional guidance.

Assessment may include questions about bowel habits and pain, an examination, and tests such as a blood test or stool testing. The results help distinguish inflammation, dehydration, infection, and other causes, and guide any change in treatment.

Seek urgent medical help for severe or rapidly worsening abdominal pain, a swollen abdomen, repeated vomiting, fainting, confusion, or inability to keep fluids down. Get prompt advice for blood in the stool, black stools, high fever, signs of dehydration such as very little urine or a dry mouth, or diarrhoea that is suddenly much worse than usual. These symptoms can need same-day assessment, especially if you have known Crohn's disease or take medicines that weaken immune responses.

Ask whether your pattern suggests active bowel inflammation, an infection, a medicine effect, or another cause; which tests are appropriate; how to maintain hydration; and which symptoms should trigger urgent review. Also ask before using an anti-diarrhoeal medicine, because some situations require a clinician's advice first.