Traveler’s diarrhea is a digestive infection you pick up from contaminated food or water, most commonly while visiting developing countries. It’s the most common travel-related illness, and bacteria cause the vast majority of cases, roughly 75% to 90%. Most episodes resolve on their own within a few days, but they can derail a trip fast if you’re not prepared.
What Causes It
The single most common culprit is a group of disease-causing strains of E. coli, particularly a type called enterotoxigenic E. coli (ETEC). These bacteria produce toxins that trigger your intestines to release fluid, leading to watery diarrhea. After E. coli, the next most frequent bacterial causes are Campylobacter, Shigella, and Salmonella.
Viruses, especially norovirus, account for about 10% to 25% of cases and tend to cause more vomiting than bacterial infections. Parasites like Giardia and Cryptosporidium make up roughly 10% of diagnoses, but they’re more common in people traveling for longer stretches. Parasitic infections also take longer to show symptoms and can linger for weeks if untreated.
Where the Risk Is Highest
Your destination matters more than almost any other factor. High-risk regions include developing countries in Latin America, Africa, the Middle East, and Asia. Intermediate-risk destinations include parts of southern Europe and some Caribbean islands. Travelers to North America, Western Europe, Japan, Australia, and New Zealand face the lowest risk, though no destination is completely safe.
The risk comes down to local water treatment, food handling standards, and sanitation infrastructure. Even luxury resorts in high-risk countries can serve contaminated food if the underlying water supply is compromised.
What It Feels Like
Traveler’s diarrhea typically hits within the first week of a trip. Bacterial cases come on quickly, often within a day or two of exposure. You’ll experience three or more loose or watery stools in a 24-hour period, frequently accompanied by cramping, nausea, and urgency. Some people also develop bloating and a low-grade fever. Most bacterial cases resolve in one to three days without treatment, though you may feel drained longer than that.
Parasitic infections behave differently. Giardia, for example, may not cause symptoms until one to three weeks after exposure, and the diarrhea tends to be more persistent, sometimes alternating with normal stools over weeks. If your symptoms start well after you’ve returned home, a parasite is more likely than a bacterium.
Warning Signs That Need Attention
Most cases are unpleasant but not dangerous. However, certain symptoms signal something more serious:
- Bloody or black stools, which may indicate a more invasive infection like Shigella or dysentery
- Fever above 102°F (39°C)
- Severe abdominal or rectal pain
- Diarrhea lasting more than two days without improvement
- Signs of dehydration, including dark urine, dizziness, dry mouth, or in children, crying without tears or unusual sleepiness
Children and older adults are more vulnerable to dehydration, so the threshold for seeking care should be lower in those groups.
How to Avoid It
Prevention comes down to what you eat and drink. The classic advice, “boil it, cook it, peel it, or forget it,” still holds. The CDC’s specific guidance is worth knowing in detail.
Avoid raw foods entirely in high-risk areas. That includes salads (even finely chopped greens can carry bacteria that clean water won’t remove), fresh salsas and condiments, cut-up fruit you didn’t peel yourself, and ceviche or any raw seafood “cooked” only in citrus juice. Street food is a common source of infection. Skip unpasteurized dairy, and don’t drink milk that’s been sitting in open containers at room temperature.
For drinks, stick to factory-sealed bottled water, and check that the seal hasn’t been tampered with. In some countries, vendors refill bottles with tap water and reseal them with a drop of glue. Avoid ice in your drinks, since it’s typically made from tap water. Don’t drink coffee or tea served lukewarm or at room temperature. Even brushing your teeth should be done with bottled or disinfected water.
Cooked food served steaming hot is generally safe. Sealed canned or bottled beverages are reliable. Fruits you peel yourself, like bananas and oranges, are a good bet.
Does a Vaccine Help?
An oral cholera vaccine (Dukoral) is sometimes marketed as offering cross-protection against ETEC-related traveler’s diarrhea. The evidence is not encouraging. Pooled results from randomized controlled trials found no meaningful benefit compared to placebo for preventing traveler’s diarrhea, including cases caused by ETEC specifically. The overall protection is estimated at roughly 6%, which is negligible. Food and water precautions remain far more effective than any available vaccine for this condition.
Treatment and Self-Care
The most important thing you can do is stay hydrated. Frequent watery stools deplete fluids and electrolytes fast, especially in hot climates. Oral rehydration solutions, available at pharmacies worldwide, contain a precise balance of salts and a small amount of glucose (2% to 3% carbohydrates) designed to help your intestines absorb water efficiently. If you can’t find a commercial packet, sipping water, broth, and diluted juice while eating salty crackers or pretzels will help in mild cases.
Loperamide (the active ingredient in Imodium) can slow diarrhea and reduce the number of trips to the bathroom. It’s useful when you need to get through a bus ride or a flight. The maximum over-the-counter dose is 8 mg per day. Don’t use loperamide if you have a high fever, bloody stools, or suspect a more invasive bacterial infection, as slowing your gut in those situations can make things worse. It’s also not safe for children under two.
For moderate to severe bacterial cases, antibiotics can shorten the illness from days to hours. Many travel medicine providers will prescribe a course for you to carry in your travel kit, to be used if symptoms are disruptive. The specific antibiotic depends on your destination, since resistance patterns vary by region. If you’re heading to Southeast Asia, for instance, certain common antibiotics are less effective due to Campylobacter resistance, and your provider will choose accordingly.
Combining loperamide with an antibiotic often provides the fastest relief for moderate cases: the antibiotic addresses the infection while loperamide controls symptoms in the meantime.
After You Get Home
Most traveler’s diarrhea resolves during the trip itself. But if you develop diarrhea days or weeks after returning, parasitic infections like Giardia become more likely and typically need specific treatment. Some people also develop a temporary period of digestive sensitivity after an episode, with loose stools, bloating, or food intolerances lasting weeks to months. This post-infectious irritable bowel syndrome affects a meaningful minority of travelers and usually improves gradually on its own.