What should you know about having diarrhoea?

Gastroenteritis and food poisoning commonly cause sudden diarrhoea, sometimes with vomiting, cramps or fever. Food intolerance can bring symptoms after a particular food. Ongoing or recurring diarrhoea may be associated with irritable bowel syndrome, coeliac disease, Crohn’s disease or an overactive thyroid. Recent travel, antibiotics and changes in diet are useful clues. The symptom pattern helps guide testing; diarrhoea alone does not identify a specific condition.

Take frequent small drinks of water or an oral rehydration solution, and replace fluids after each loose stool. Eat small, plain meals when able; avoid alcohol and foods that clearly worsen symptoms. Wash hands with soap and water and avoid preparing food for other people while unwell. Do not use anti-diarrhoeal medicine if you have blood in the stool or a high fever without asking a clinician. Keep track of onset, frequency, travel, medicines and foods.

Seek urgent help for fainting, confusion, very little urine, inability to keep fluids down, severe abdominal pain, black stools or visible blood. Contact a clinician promptly for fever with marked illness, symptoms after antibiotics, or diarrhoea that does not settle. Babies, older adults and people with significant health conditions can become dehydrated quickly and may need earlier advice.

Could an infection, food intolerance or medicine explain this? Do I need testing? Which fluids are suitable? When can I return to work or prepare food? What signs would mean I need urgent care?