What should you know about sickness and diarrhoea abroad?

A change in local bacteria, unsafe drinking water, inadequately cooked food or poor hand hygiene can lead to gastroenteritis or food poisoning. Giardiasis may follow contaminated water and can cause prolonged diarrhoea. A new food intolerance can also upset the gut, while coeliac disease, Crohn's disease or irritable bowel syndrome may explain symptoms that continue after the trip. Vomiting and loose stools can have several causes, so the timing, fever, pain and travel exposures matter.

Use sealed bottled water or water that has been safely treated for drinking, brushing teeth and making ice. Take frequent small sips of a suitable oral rehydration drink, especially after each loose stool. Rest, eat simple foods when able, and avoid alcohol and foods that seem to worsen symptoms. Wash hands with soap and water; hand gel is less reliable when hands are visibly dirty. Keep a note of when symptoms began, what you ate, and any medicines taken.

Use local medical services urgently if you cannot retain fluids, feel faint, become confused, pass very little urine, or have blood in vomit or stools. Severe abdominal pain, high fever, breathing difficulty or marked weakness also needs prompt assessment. Arrange a review after returning if diarrhoea persists, recurs, or began after potentially unsafe water exposure. Tell the clinician where you travelled and whether anyone else became ill.

Could this be travel-related infection, food poisoning or a condition that needs testing? Which rehydration product is suitable, and should I be tested if symptoms continue after returning? Are there medicines I should avoid with my existing conditions?