Published 29 June 2026

Traveller's Diarrhoea: Prevention, Treatment, and When to Worry

Traveller's diarrhoea is the most common health complaint among international travellers. Eighty million people contract it every year. Studies consistently find that between 30% and 70% of travellers to high-risk destinations develop it within the first two weeks of their trip, depending on the destination and the time of year. The CDC Yellow Book puts the likelihood of developing it during a two-week stay in India at above 60%. For South and Southeast Asia, sub-Saharan Africa, and Latin America more broadly, the risk is high enough that experienced travel health professionals advise preparing for it as a near-certainty rather than a remote possibility.

Most cases are unpleasant but resolve on their own within one to three days. A small percentage become severe enough to require antibiotics and, in some cases, hospitalisation. Knowing the difference — and knowing what to do in both situations — is what this guide covers.

What Traveller's Diarrhoea Actually Is

Traveller's diarrhoea (TD) is defined clinically as three or more unformed stools in twenty-four hours, often accompanied by at least one of the following: stomach cramps, nausea, vomiting, fever, or blood in the stool. It is caused by consuming food or water contaminated with infectious organisms — bacteria, viruses, or parasites.

Bacteria are responsible for the vast majority of cases. According to the CDC Yellow Book, the most common pathogens are diarrheagenic Escherichia coli strains — most prominently enterotoxigenic E. coli (ETEC), but also enteroaggregative and enteropathogenic E. coli — followed by Campylobacter jejuni, Shigella species, and Salmonella species. Research published in military travel cohorts found E. coli strains identified in 67% to 82% of cases across six countries. Bacterial pathogens account for over 80% of cases overall.

Norovirus is the most significant viral cause, accounting for 10–20% of cases. Rotavirus is also relevant, particularly in children. Among parasites, Giardia intestinalis is the most frequently identified, followed by Cryptosporidium. Parasitic infections are less common than bacterial ones but tend to cause more prolonged illness — Giardia in particular can produce weeks of symptoms if untreated.

The causative organism varies by destination, which matters for treatment decisions. In Southeast Asia, particularly Thailand, Campylobacter rivals or exceeds ETEC as the most common bacterial cause — and fluoroquinolone-resistant strains of Campylobacter are now prevalent in virtually all regions of the world, especially Southeast Asia. In Latin America, Africa, South Asia, and the Middle East, ETEC dominates. This regional variation is why antibiotic choice differs by destination. Sources: CDC Yellow Book — Traveller's Diarrhoea, updated March 2026 | PMC — Resistant Pathogens as Causes of Traveller's Diarrhea | NIH — Etiology and Epidemiology of Travellers' Diarrhea 2018–2023

High, Intermediate, and Low Risk Destinations

Not every destination carries equal risk. The CDC categorises countries into three tiers based on documented TD attack rates.

High risk destinations — where TD affects 20–70% of travellers — include South and Southeast Asia, most of sub-Saharan Africa, and most of Latin America. This covers the world's most popular long-haul travel destinations: India, Thailand, Indonesia including Bali, Vietnam, Cambodia, Nepal, Kenya, Tanzania, Ghana, Nigeria, Mexico, Brazil, Peru, Colombia, Morocco, and Egypt.

Intermediate risk destinations — where TD affects around 8–20% of travellers — include parts of Eastern Europe, South Africa, some Caribbean islands, and some Middle Eastern countries.

Low risk destinations — where TD risk is comparable to home — include Western and Northern Europe, North America, Australia, New Zealand, Japan, and Singapore.

Risk is highest in the first two weeks of travel, among younger adults, and among those eating at local restaurants and street stalls rather than in international hotel restaurants. The type of accommodation matters: staying in budget guesthouses or camping carries a higher risk than staying in established hotels with controlled kitchen standards. Sources: CDC Yellow Book — Traveller's Diarrhoea

Prevention: What Actually Works

Food and Water Hygiene

The most important prevention measure is what you eat and drink. The classic traveller's rule — boil it, cook it, peel it, or forget it — remains the foundation of food safety abroad. These are not just precautionary habits; they are evidence-backed risk reduction measures. Here is what the CDC recommends.

Drink only bottled water with an unbroken seal, or water that has been boiled or purified with iodine tablets or a certified filter. This applies everywhere in high-risk destinations, including in established hotels. Do not drink tap water or use it to rinse your mouth. In rural or budget settings, use bottled water even for brushing teeth. Be cautious with ice — it may be made from tap water, particularly at small local restaurants and street stalls. Ice at major international hotels and established restaurants is generally made from purified water.

Eat fully cooked food served hot. Avoid raw salads and unpeeled fruit bought from street stalls. Be cautious with raw or undercooked seafood, particularly shellfish, which concentrate pathogens. Avoid buffets where food has been sitting at room temperature. Wash your hands thoroughly with soap and water before eating. When handwashing is not possible, use a hand sanitiser with at least 60% alcohol as a backup.

Street food is not inherently unsafe — the cooking process kills most pathogens if food is served freshly cooked and piping hot. The risk with street food comes from dishes that have been sitting out, reheated, or prepared with contaminated water in the cooking process itself.

Probiotics

Some evidence suggests that certain probiotic strains may reduce the incidence or severity of TD, though results from clinical trials have been mixed and no specific probiotic is formally recommended by the CDC or WHO for this purpose. If you already take a probiotic regularly, continuing it during travel is unlikely to cause harm. Starting a course before departure is a low-risk intervention that some travellers find helpful.

Antibiotic Prophylaxis: Generally Not Recommended

Taking antibiotics daily to prevent TD is not recommended by the CDC for most travellers, despite the fact that studies have shown antibiotic prophylaxis can reduce attack rates by 90% or more. The reasons are practical and public-health driven: routine antibiotic use contributes to antimicrobial resistance, increases the risk of C. difficile infection, may cause side effects, and does not protect against viral or parasitic causes of TD.

Prophylactic antibiotics may be considered by travel health professionals for specific high-risk travellers — those who are immunocompromised, those with inflammatory bowel disease, or those for whom even a short illness would be medically dangerous or professionally catastrophic. This is an individual clinical decision. Do not start antibiotic prophylaxis without medical guidance. Sources: CDC Yellow Book — Traveller's Diarrhoea | Journal of Travel Medicine — Guidelines for Prevention and Treatment of Travellers' Diarrhea, PMC

Treatment: A Severity-Based Approach

The CDC Yellow Book and the Journal of Travel Medicine expert panel both recommend a severity-based treatment framework. What you should do depends on how sick you are.

Mild TD: Oral Rehydration, Not Antibiotics

Mild TD is defined as diarrhoea that is tolerable, not distressing, and does not significantly interfere with your planned activities. This covers most cases.

The cornerstone of treatment at this stage is oral rehydration. Diarrhoea and vomiting cause significant fluid and electrolyte loss, particularly in hot climates where you are already losing fluid through sweat. Oral rehydration salts (ORS) — small sachets you dissolve in clean water — are the most effective way to replace what you are losing. They are available at pharmacies throughout the world, including at virtually every pharmacy in Thailand, India, Indonesia, and across Africa and Latin America. You should pack some for your kit regardless.

If you do not have ORS, homemade rehydration solution can be made with one litre of boiled or bottled water, six level teaspoons of sugar, and half a teaspoon of salt. Drink small amounts frequently rather than large quantities at once.

Loperamide (sold as Imodium and generic equivalents) is an antimotility drug that reduces the frequency of diarrhoea by slowing gut movement. It is not a treatment for the underlying infection but is useful for managing symptoms when you need to travel or function. It should not be used alone if you have fever or bloody stools — see the warning below. Sources: TeleDirectMD — Traveller's Diarrhea Treatment | PMC — Prevention and Self-Treatment of Traveller's Diarrhea

Moderate TD: Consider Antibiotics

Moderate TD is diarrhoea that is distressing or interferes significantly with your planned activities. At this point, antibiotic treatment is worth considering, particularly if symptoms are not improving after twenty-four hours.

Azithromycin is the current first-line antibiotic recommended by the CDC for TD in South Asia (India, Nepal, Bangladesh) and Southeast Asia (Thailand, Vietnam, Cambodia, Indonesia), specifically because of the high prevalence of fluoroquinolone-resistant Campylobacter in these regions. A single dose of azithromycin 1,000 mg, or 500 mg daily for three days, is the standard regimen for adults. A prospective cohort study published in ScienceDirect found that Campylobacter was identified in 20% of TD cases in South Asia and 15% of cases in Southeast Asia — high enough proportions to make azithromycin the default choice over fluoroquinolones in these regions.

For destinations outside South and Southeast Asia — Latin America, Africa, the Middle East — fluoroquinolones (ciprofloxacin or levofloxacin) or azithromycin are both appropriate options, though resistance is increasing globally and azithromycin is increasingly preferred across all destinations.

Loperamide can be used alongside antibiotics to reduce stool frequency and manage symptoms — but not alone in moderate-to-severe cases, and not if you have fever or bloody stools. Sources: CDC Yellow Book — Traveller's Diarrhoea | Journal of Travel Medicine — Guidelines for Prevention and Treatment, PMC | ScienceDirect — Prospective Study of Travellers' Diarrhoea Pathogens by Destination

Severe TD: Seek Medical Attention

Severe TD is diarrhoea that is incapacitating or is accompanied by signs of systemic illness. Seek medical care rather than trying to manage it on your own.

When to Stop Self-Treating and See a Doctor

This is the most important section of this guide. The following symptoms in the context of diarrhoea abroad indicate that you should stop self-treating and get to a medical facility as quickly as possible.

Blood or mucus in the stool. This indicates dysentery — an invasive bacterial infection affecting the bowel lining. Dysentery requires antibiotic treatment, and loperamide should not be used, as it can worsen outcomes by slowing the passage of toxin-producing bacteria through the gut.

High fever. Fever above 38.5°C (101.3°F) alongside diarrhoea suggests systemic infection rather than straightforward gastroenteritis.

Signs of severe dehydration. These include dizziness on standing, a significantly reduced amount of urine (or very dark urine), rapid heartbeat, confusion or disorientation, or sunken eyes. Severe dehydration can become dangerous quickly, particularly in children and the elderly, and may require intravenous fluid replacement.

Diarrhoea that does not improve within forty-eight to seventy-two hours despite antibiotic treatment. This may indicate a resistant organism, a non-bacterial cause such as Giardia, or a more serious condition.

Any diarrhoea combined with fever in someone who has been in a malaria-endemic area. Fever after travel to a malaria zone must be evaluated to exclude malaria, regardless of whether diarrhoea is present.

Diarrhoea in infants and young children. Children dehydrate significantly faster than adults. Any diarrhoea in a child under two should be assessed by a doctor promptly. Sources: CDC Yellow Book — Traveller's Diarrhoea | Merck Manual — Traveller's Diarrhea

The Long-Term Consequence Most People Don't Know About

Post-infectious irritable bowel syndrome (PI-IBS) is a recognised complication of TD that is significantly underappreciated. Research published in PMC found that the risk of developing PI-IBS is five times higher in returning travellers who had TD during their trip than in travellers who did not. An estimated 5–10% of people who develop TD go on to experience chronic functional bowel problems — altered bowel habits, cramping, bloating — that can persist for months or years after returning home.

This is not a reason to avoid travel, but it is a reason to take TD seriously when it occurs, to treat it appropriately rather than simply waiting it out, and to see your GP if gut symptoms persist for more than a few weeks after you return home. Sources: PMC — New Developments in Traveller's Diarrhea

What to Pack

A basic TD kit for any high-risk destination should include oral rehydration salts (ORS sachets), loperamide (Imodium) for symptomatic management of non-severe cases, a standby antibiotic if prescribed by your travel health professional before departure (azithromycin for Asia; ciprofloxacin or azithromycin for other high-risk destinations), hand sanitiser with at least 60% alcohol, and a digital thermometer.

Your travel health professional can prescribe a standby antibiotic before your trip at your pre-travel appointment. This allows you to start treatment as soon as moderate symptoms develop without needing to find a pharmacy or clinic in an unfamiliar location. It is one of the most practically useful things you can arrange before a trip to a high-risk destination.

Useful Internal Resources

See the interactive map on Travel Vaccine Map to check the health risk level for your destination. For destination-specific advice on food and water risks, see our guides to Thailand, Bali, India, East Africa, and South America. For timing your pre-travel appointment, see How Far in Advance Should You See a Travel Doctor?

Sources

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This article is for informational purposes only and does not constitute medical advice. Always consult a qualified travel health professional or GP before travel.