Does coeliac disease cause diarrhoea?

In coeliac disease, gluten triggers an immune response in the small intestine. Damage to the intestinal lining can reduce normal absorption and alter the way stools form. This may cause frequent loose or watery stools, urgency, excess gas, abdominal discomfort or pale, bulky stools. Symptoms can be ongoing or fluctuate, and some people have constipation instead. Infection, medicines, irritable bowel syndrome and other conditions can also cause diarrhoea, so the symptom needs context rather than a diagnosis based on its presence.

A clinician may recommend coeliac blood tests and sometimes further assessment. If testing is planned, ask whether you should continue eating gluten beforehand; removing it without advice can make results harder to interpret.

Book an appointment when diarrhoea lasts beyond a short illness, repeatedly returns, or is paired with bloating, fatigue or weight loss. Note how often you pass stool, whether there is urgency, and any relationship with meals. Replace fluids regularly, especially if stools are frequent, and ask a pharmacist or clinician about suitable rehydration options. Avoid starting a gluten-free diet before discussing coeliac testing, and do not use anti-diarrhoeal medicine when you have blood in the stool or significant fever unless a clinician advises it.

Get urgent medical care for blood or black stool, severe abdominal pain, repeated vomiting, confusion, fainting, or dehydration with very little urine, a dry mouth or pronounced dizziness. Seek prompt clinical advice if diarrhoea is persistent, wakes you from sleep, follows recent antibiotics, or occurs with ongoing weight loss or fever.

Could coeliac disease be contributing to my diarrhoea? Which blood tests are appropriate? Should I continue gluten until testing is finished? Do I need stool tests or checks for anaemia and nutrient problems? What fluid plan is suitable for me?