Causes of persistent diarrhoea

Food poisoning, gastroenteritis, or giardiasis may leave loose stools during or after an infection. Food intolerance can cause symptoms after particular foods. Coeliac disease affects the response to gluten and may lead to ongoing digestive symptoms. Crohn's disease can cause diarrhoea with abdominal pain or fatigue. Irritable bowel syndrome may bring recurring diarrhoea with abdominal discomfort and bloating. An overactive thyroid can speed up bowel movements. The stool appearance, travel history, diet, medicines, pain, and associated symptoms help a clinician narrow the possibilities.

Drink regularly and replace fluids after loose stools; oral rehydration advice may be useful if losses continue. Record frequency, appearance, meals, travel, medicines, fever, pain, and blood or mucus. Choose simple foods you tolerate while symptoms settle, and avoid foods that clearly trigger them. Do not begin a restrictive gluten-free diet before discussing possible coeliac testing, because changing the diet can affect assessment. A clinician may arrange stool or blood tests based on the pattern.

Seek prompt medical advice for persistent diarrhoea, dehydration symptoms, blood or black stools, fever, severe abdominal pain, repeated vomiting, or marked weakness. Urgent care is needed for confusion, fainting, inability to keep fluids down, or rapidly worsening symptoms. Babies, older adults, and people with significant medical conditions can become dehydrated quickly.

Could infection, food intolerance, coeliac disease, inflammatory bowel disease, or thyroid disease fit my pattern? Do I need stool or blood testing? Which foods, medicines, or fluids should I use while this is investigated?