How to Prevent Traveler's Diarrhea

What is traveler’s diarrhea and what causes it?

Traveler’s diarrhea (TD) is defined as three or more loose stools in 24 hours while abroad, often accompanied by cramps, nausea, bloating, or urgency. Bacteria cause an estimated 75–90% of cases, with enterotoxigenic *Escherichia coli* (ETEC) being the most commonly identified pathogen 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance. Other bacterial culprits include *Campylobacter jejuni*, *Shigella*, and *Salmonella* species. Viruses account for roughly 10–25% of cases, while protozoal parasites such as *Giardia lamblia* and *Cryptosporidium* represent a smaller share but tend to cause more prolonged illness 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance.

Risk is highest in South and Southeast Asia, Sub-Saharan Africa, Mexico, Central and South America, and parts of the Middle East. Within any country, eating at venues with uncertain food-handling practices — street stalls, small local restaurants, open buffets — carries higher risk than hotels with controlled kitchens 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance.

What food and water habits actually prevent it?

Consistently applying these habits throughout your trip — not just on arrival day — is key 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance.

Avoid: - Tap water, ice made from tap water, or any beverage diluted with unboiled water - Unpeeled raw fruits and vegetables, especially if washed in tap water - Raw or undercooked shellfish, meat, or fish - Street food or buffet items sitting at room temperature - Unpasteurized dairy products

Safe choices: - Commercially sealed bottled or canned water and beverages - Hot food served steaming — heat kills most pathogens - Fruits you peel yourself (banana, orange, mango with intact skin) - Packaged foods from sealed containers - Coffee and tea made with fully boiling water

When bottled water is unavailable: Boiling is the most reliable purification method. Chlorine dioxide tablets and portable filters can also be effective — check that any filter meets specifications for removing protozoa, bacteria, *and* viruses, as not all portable filters do 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance.

Does handwashing matter?

Yes. Washing hands with soap and clean water before eating and after using the toilet is one of the most effective preventive measures available and costs nothing. When soap and clean water are unavailable, an alcohol-based hand sanitizer (at least 60% alcohol) is a reasonable substitute, though it is less effective against certain pathogens such as *Cryptosporidium* 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance. Pack a small hand sanitizer bottle when traveling in lower-resource settings.

Do any medications prevent traveler’s diarrhea?

Bismuth subsalicylate (the active ingredient in Pepto-Bismol) reduces TD incidence by approximately 50% when taken at the recommended preventive dose 2Ref 2Brum JM, Gibb RD, Ramsey DL, Balan G, Yacyshyn BR (2020).Systematic Review and Meta-Analyses Assessment of the Clinical Efficacy of Bismuth Subsalicylate for Prevention and Treatment of Infectious Diarrhea.Bismuth subsalicylate reduces traveler’s diarrhea incidence by approximately 50% compared with placebo (meta-analysis of randomized controlled trials). However, it requires frequent daily dosing, turns stools and tongue black, is not suitable for people on aspirin therapy, children, or pregnant individuals, and is not routinely recommended for most healthy adult travelers.

Antibiotics are generally not recommended for routine prevention — overuse accelerates resistance, and side effects are real. Some clinicians consider short-term antibiotic prophylaxis in specific high-risk situations (immunocompromised travelers, critical business trips). That is a personalized clinical decision, not a self-prescribing one.

Standby self-treatment: Many travel medicine clinicians recommend that travelers carry a short antibiotic course for self-treatment if moderate-to-severe TD develops 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance. Which antibiotic depends on destination resistance patterns and your health history — discuss this at your pre-travel appointment.

What is oral rehydration and why does it matter?

Replacing lost fluid and electrolytes is the cornerstone of managing TD when it strikes — more important than stopping the stooling quickly. Oral rehydration salts (ORS) are widely available at pharmacies in most lower-income countries. Plain water or sports drinks are less effective than a properly formulated ORS, because the glucose-sodium ratio in ORS is specifically designed to maximize intestinal absorption during acute diarrheal illness 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance. For mild diarrhea without fever or blood, staying well hydrated and resting is often sufficient.

Who needs extra planning before high-risk travel?

Certain groups require more careful pre-travel preparation:

• Immunocompromised travelers (HIV, organ transplant, immunosuppressive medications): at higher risk for severe and prolonged TD; prophylactic antibiotics may be considered 1Ref 1Centers for Disease Control and Prevention (2024).Travelers’ Diarrhea — Yellow Book.Causative organisms (ETEC and others), high-risk destinations, food and water precautions, role of bismuth subsalicylate (~50% reduction), standby antibiotic treatment, and oral rehydration guidance
• Inflammatory bowel disease (IBD): TD can mimic a flare; coordinate with your gastroenterologist before travel
• Children: dehydrate faster than adults; carry ORS packets at all times
• Pregnancy: dehydration carries fetal risk, and many antibiotics are contraindicated; discuss a plan with your OB provider
• Aspirin therapy or salicylate sensitivity: bismuth subsalicylate contains salicylate and should be avoided