Travellers' diarrhea is the most common illness that affects travellers. Most cases clear up in a few days, but it can spoil a trip. Here is what Canada's travel medicine committee, CATMAT, and the Government of Canada advise.

How common it is, and who gets it

In studies of travellers from high-income countries, 20% to 90% got it during a two-week stay in a higher-risk region. The Government of Canada rates developing countries in Central and South America, Mexico, Africa, the Middle East and Asia as high risk.

Backpackers get it more often than beach-resort guests, and adults aged 30 or younger more often than older adults. Medicines that lower stomach acid make some bacterial infections more likely. People visiting friends and relatives are more likely to eat local food and drink untreated water. In adults it starts, on average, on day three or four of the trip and lasts three to four days. Up to 10% of cases lead to diarrhea lasting two weeks or more, or another complication.

Food, water and handwashing: what the evidence says

CATMAT's review found no clear link between following food rules and getting sick, though the studies were weak. It still recommends handwashing and careful food and drink choices. Outside travel, promoting handwashing cuts diarrhea episodes by about a third.

Boil it, cook it, peel it or leave it. Eat food that is well cooked and served hot. Avoid raw or undercooked meat and seafood, salads and street food.
Drink safe water: boiled, disinfected or commercially sealed. Sealed carbonated drinks are generally safe. Avoid ice unless made from purified water, and brush your teeth with safe water.
Wash your hands with soap for at least 20 seconds, or use a sanitizer with at least 60% alcohol, before eating and after using the bathroom.

Only some food-borne infections, such as hepatitis A and typhoid, can be prevented with vaccines.

Is Dukoral worth it?

Dukoral is an oral cholera vaccine that is also used against ETEC, a common cause of travellers' diarrhea. CATMAT recommends against using it routinely for travellers' diarrhea: in the trials it reviewed, 35% of vaccinated travellers still got diarrhea, compared with 37% given a placebo. Canada's immunization guide puts its overall protection at about 6%.

It may still suit some short-term travellers at high risk of complications or serious inconvenience: people who can't afford even a brief illness, such as elite athletes; people with no stomach acid, part of the stomach removed or repeated severe bouts; young children over 2; and people with a weakened immune system or a chronic illness that makes diarrhea more dangerous. It is not recommended under age 2. See our Dukoral guide.

Pepto-Bismol, probiotics and preventive antibiotics

Bismuth subsalicylate (Pepto-Bismol), sold without a prescription, is the only product CATMAT strongly recommends for prevention, for adults at significant risk. In trials it prevented about 250 cases per 1,000 travellers. CATMAT's preventive dose for adults is two 262 mg tablets four times a day, for no more than three weeks. It can turn your tongue and stool black, which is harmless. It is not for children, or for people who are pregnant, breastfeeding or allergic to aspirin. Your physician decides whether it suits you, especially if you take other medicines.

Probiotics: CATMAT found too little evidence to recommend them. Preventive antibiotics are not for routine use; CATMAT says the risks and benefits must be weighed for each person.

If you get sick: fluids come first

Start drinking extra fluids as soon as diarrhea starts. Most healthy adults can keep up with purified water, clear soups, or diluted juice or sports drinks. Children, older adults and people with medical conditions should consider an oral rehydration solution (ORS).

Buy ORS packets in Canada before you leave. Mix them with boiled or treated water exactly as the package says.
Homemade mixes are not recommended for treating dehydration. Use one only as a stopgap on the way to medical care, if you have no packets.
Give children under 2 about 50 to 100 mL after each loose stool, and children aged 2 to 9 about 100 to 200 mL.
Keep eating, keep babies on breast milk or formula, and avoid alcohol and caffeinated or sugary drinks.

Loperamide: helpful, with limits

Loperamide (Imodium) is sold without a prescription and shortens diarrhea. The usual adult dose, on the Canadian label and in CATMAT's table, is 4 mg to start, then 2 mg after each loose stool, up to 16 mg a day. Ask your physician whether it suits you.

Don't use it if there is blood in your stool or you have a fever.
Stop and see a doctor or pharmacist if diarrhea gets worse or lasts more than 48 hours.
Never take more than directed. The label warns this can cause serious heart problems or death.
It is not for children under 2, and under 12 only on a doctor's advice. Ask first if you are pregnant or breastfeeding.

Standby antibiotics: what Canada recommends

CATMAT's rule is to use antibiotics as little as possible because of side effects and resistance. Treat mild diarrhea with fluids and loperamide or bismuth subsalicylate; an antibiotic may be justified if that fails or symptoms are more serious. In 2023 CATMAT added that routine antibiotic use should be avoided, keeping antibiotics for severe bacterial illness or people at higher risk, such as those with weakened immunity.

Which drug: CATMAT found azithromycin works about as well as fluoroquinolones such as ciprofloxacin.
South and Southeast Asia: CATMAT advises caution with fluoroquinolones for the Indian subcontinent and Southeast Asia because of resistance; azithromycin is the alternative there.
Safety: Health Canada warns that fluoroquinolones can, rarely, cause disabling side effects that persist, involving tendons, nerves and the brain.
Mexico: a multidrug-resistant Salmonella has been reported in Canadians returning from Mexico, and CATMAT says azithromycin and fluoroquinolones are likely to be ineffective against it. Diarrhea with fever for more than 48 hours after a recent trip there needs a doctor.

Azithromycin and fluoroquinolones are prescription-only in Canada. The physician decides whether you need one, which one, the dose and when to start it. Book a $110 virtual consultation with a physician licensed in Ontario; you must be in Ontario during the video call. Prescriptions go to our Toronto pharmacy, Cloud Pharmacy at 55 Dundas St E, where pharmacists also give travel vaccines.

Children, pregnancy and chronic illness

Children become dehydrated more quickly than adults, so use ORS. Avoid bismuth subsalicylate. CATMAT says children under 18 should, in most cases, get azithromycin rather than a fluoroquinolone. See travel vaccines for children.

Pregnancy: food- and water-borne illnesses can be more severe in pregnancy. Avoid bismuth subsalicylate, iodine water tablets and fluoroquinolones, and ask before using loperamide. Dukoral is considered only in high-risk situations, such as an outbreak. More in travel vaccines and pregnancy.

Chronic illness or weakened immunity: people who are immunosuppressed or have kidney failure, heart failure, insulin-dependent diabetes or inflammatory bowel disease face a higher risk of serious consequences. Plan to use ORS, and ask about Dukoral or preventive antibiotics.

When to see a doctor

Get medical care for blood in your stool (even if other symptoms are mild), a high fever, persistent vomiting, severe abdominal pain, yellow skin, signs of dehydration, or diarrhea that isn't improving despite ORS. Get help right away if an infant or young child has signs of dehydration, bloody diarrhea, a fever or persistent vomiting. In pregnancy, get care right away for persistent vomiting or diarrhea, or dehydration.

CATMAT says anyone with fever and diarrhea who has been in a malaria area needs malaria blood tests right away; see our malaria prevention guide. Back home, see a health care provider if you were sick while away or get sick later, and say where you travelled. Diarrhea lasting more than two weeks should be checked by a doctor. More on illness after travel.

Frequently asked questions

Should I take an antibiotic as soon as diarrhea starts?

Usually not. For mild diarrhea, CATMAT advises fluids plus loperamide or bismuth subsalicylate, with an antibiotic only if that fails or symptoms are more serious.

Am I safe at an all-inclusive resort?

Safer than backpacking, but not risk-free. Luxury accommodation doesn't necessarily lower the risk, and about 30% of cases seen at Canadian GeoSentinel clinics were picked up in the Caribbean or Central America, including Mexico.

Does Dukoral replace food and water precautions?

No. Canada's immunization guide says prevention relies mainly on careful food and water choices and good hygiene, not vaccination.

Travellers' Diarrhea: Prevention and Self-Treatment for Canadians