Why does coeliac disease cause diarrhoea?

The small intestine normally absorbs nutrients and fluid as food moves through it. In coeliac disease, the immune response to gluten injures this lining. Poorer absorption can lead to loose, frequent, urgent, or bulky stools, along with wind, cramps, bloating, fatigue, or weight change.

Diarrhoea is a common presentation of Coeliac Disease. Diarrhoea can also result from infections, medicines, food intolerance, inflammatory bowel conditions, and other causes, so its presence does not establish a diagnosis.

If diarrhoea is ongoing or keeps returning, arrange a clinical assessment. When coeliac disease is being considered, do not begin a gluten-free diet before discussing testing, because it can change test results. A clinician can assess hydration, review medicines, arrange relevant tests, and advise on dietary management if coeliac disease is confirmed.

Drink fluids regularly and consider oral rehydration solution if a clinician or pharmacist recommends it. Keep track of stool frequency, blood or mucus, fever, recent travel, food exposures, and signs that you are becoming dehydrated.

Seek urgent care for blood in the stool, black stools, severe abdominal pain, confusion, fainting, very little urine, or inability to keep fluids down. Obtain prompt medical advice for high fever, persistent vomiting, symptoms of dehydration, unexplained weight loss, or diarrhoea that does not settle.

Could my diarrhoea be related to coeliac disease, an infection, or medication? Do I need testing before dietary changes? What should I drink or eat while symptoms are active, and which warning signs need urgent care?