Diarrhoea abroad: what to know

A change in local microbes, untreated water, raw food, undercooked meals, or poor hand hygiene can irritate the bowel or cause an infection. Food poisoning and gastroenteritis are common explanations. Giardia can cause prolonged, foul-smelling or greasy stools after exposure to unsafe water. Symptoms that continue after returning may also reflect a food intolerance or a condition such as Crohn's disease, coeliac disease, or irritable bowel syndrome rather than a short-lived infection.

Diarrhea can drain water and salts quickly. Dry mouth, intense thirst, dizziness, unusual sleepiness, and reduced urine are signs to take seriously.

Use sealed bottled water or a safe treated supply for drinking and brushing teeth. Take frequent sips of an oral rehydration drink and choose simple foods as appetite returns. Wash hands with soap, avoid preparing food for others while unwell, and avoid alcohol until you have recovered. Do not start leftover antibiotics or someone else's medicine. Keep a note of destinations, water exposures, meals, medicines, fever, and stool changes for a clinician.

Seek urgent help for fainting, confusion, severe dehydration, severe abdominal pain, black or bloody stool, or a high fever with worsening weakness. Get medical advice during the trip if you cannot drink enough, and arrange review after travel if symptoms persist, recur, or include weight loss or blood. Mention every country visited and any untreated water exposure; testing may be needed for a travel-related infection.

Could this be a travel-related infection? Do I need stool testing? How should I replace fluids? Which foods and drinks should I avoid, and what symptoms require urgent care?