This article is general information, not medical advice. Speak to a doctor or pharmacist before taking any medicine, especially for children, during pregnancy, or if you have a health condition or take other medicines.
It is the illness travellers talk about least and catch most. The US CDC calls travellers' diarrhoea "the most predictable travel-related illness", with attack rates of 30% to 70% of travellers over a 2-week period, depending on the destination and the season. Most cases are mild and short. Knowing how to lower the risk, and when it's more than an upset stomach, makes a real difference.
What causes it
According to the CDC, bacteria cause most cases, 75% to 90% or more, with a type of E. coli the most common. Viruses and, less often, parasites cause the rest. Symptoms of bacterial and viral infections usually start between 6 and 96 hours after exposure.
The source is almost always food or water contaminated with traces of faeces, which is why hygiene where food is prepared matters more than the type of restaurant.
Lowering the risk: food
The CDC's food and water guidance says fully cooked foods served hot are safest. In practice:
- Choose: dishes cooked through and served steaming hot; fully cooked meat and eggs; fruit you peel yourself after rinsing it in safe water; pasteurised milk and dairy.
- Be careful with: raw or undercooked meat, fish, shellfish and eggs; salads and raw vegetables; fruit that is already cut; unpasteurised milk and cheese.
- Street food: the CDC notes that eating from street vendors increases the risk of illness. If you do, choose busy stalls where food is cooked in front of you and served hot.
Lowering the risk: drinks and water
- Sealed drinks are generally safe: water, fizzy drinks, commercially prepared juices and alcohol in unopened, factory-sealed bottles or cans.
- Hot drinks made with water that has just boiled, such as tea and coffee, are generally safe.
- Ice and fountain drinks are a common trap: the ice may be made from contaminated water.
- Tap water: where it may be unsafe, use sealed or treated water for drinking and for brushing your teeth.
If you need to treat water yourself, the CDC recommends bringing clear water to a rolling boil for 1 minute, or 3 minutes at altitudes above 6,500 feet (about 2,000 metres).
Wash your hands. Use soap and water before preparing or eating food. When there is no sink, the CDC advises a hand sanitiser containing at least 60% alcohol, then washing your hands when you can.
Can you prevent it with medicine?
The CDC reports that bismuth subsalicylate, the active ingredient in some stomach remedies, reduces travellers' diarrhoea by about 50%. It isn't suitable for everyone, for example children or people taking certain medicines, so ask a pharmacist first.
Antibiotics are not recommended to prevent it for most travellers. The CDC reserves that for high-risk people, such as those with weakened immune systems, on short trips.
If it starts
Drink first
Most cases get better on their own. The NHS says diarrhoea usually stops within 5 to 7 days, and the most important thing is to drink plenty of fluids to avoid dehydration: small, frequent sips. The CDC gives typical durations of 3 to 7 days for untreated bacterial diarrhoea and 2 to 3 days for viral diarrhoea.
Oral rehydration salts, sold in pharmacies worldwide, replace the water and salts you lose and are worth carrying, especially with children. Eat when you feel able, and avoid fatty or spicy food for a while.
Medicines
Anti-diarrhoea medicines such as loperamide can reduce the number of trips to the toilet in adults. The CDC says these medicines are not recommended if you have bloody diarrhoea or fever. Antibiotics are for moderate or severe cases and should be chosen with a doctor, because resistance differs between regions.
Children
The CDC notes that babies and young children are at greater risk of dehydration. Start oral rehydration early and get medical advice sooner than you would for an adult.
When to see a doctor
Get medical help if you have:
- blood in your stool;
- a high temperature;
- signs of dehydration, such as dizziness, very little or dark urine, or a dry mouth, that don't improve with oral rehydration salts;
- severe stomach pain;
- diarrhoea that lasts more than 7 days, which the NHS lists as a reason to seek help.
Keep your travel insurance details at hand: most policies have a 24-hour medical assistance line that can direct you to a suitable clinic.
After you recover
The NHS advises staying off school or work until you have not been sick or had diarrhoea for at least 2 days. On holiday, give yourself a gentler day or two before long journeys or heavy meals.
How common is travellers' diarrhoea?
Very common. The CDC reports attack rates of 30% to 70% of travellers over a 2-week period, depending on the destination and season.
How long does it usually last?
The NHS says diarrhoea usually stops within 5 to 7 days. The CDC gives 3 to 7 days for untreated bacterial diarrhoea and 2 to 3 days for viral diarrhoea.
Is ice safe to drink abroad?
Only if you are reasonably sure it was made from safe water. The CDC advises avoiding ice and fountain drinks where tap water may be unsafe.
When should I see a doctor?
If there is blood in your stool, a high temperature, severe pain, signs of dehydration that don't improve, or if it lasts more than 7 days.
Sources
- CDC Yellow Book — Travelers' Diarrhea (checked September 30, 2026)
- CDC Yellow Book — Food and Water Precautions for Travelers (checked September 30, 2026)
- NHS (UK National Health Service) — Diarrhoea and vomiting (checked September 30, 2026)
About the author
Bookskies Editorial TeamBookskies uses AI for drafts and translations. This organizational byline does not identify a named expert or certify a human review. Check the guide’s sources and documented review status before relying on time-sensitive claims.
