No one wants to spend a long-awaited getaway in the bathroom. But plenty of vacationers do, thanks to bacteria, viruses and other bugs that bring gastrointestinal distress to 20 to 50 percent of international travelers each year, according to the Centers for Disease Control and Prevention (CDC). 

Travelers’ diarrhea is the most common illness among people visiting less-developed areas of the world. Your risk is highest in Latin America, Africa, Asia and parts of the Middle East, according to CDC. It’s lowest in the United States, Canada, Northern and Western Europe, Australia, New Zealand and Japan. But travel medicine experts warn that you could pick it up in destinations you may think are safe, such as Eastern Europe and some of the Caribbean islands.

Fecal bacteria in contaminated water — and in foods grown or washed in that water — are the top cause of Montezuma’s revenge according to Johnnie Yates, MD, of the Clinic Travel Medicine Center in Kathmandu, Nepal. Yates notes in the journal American Family Physician that “avoiding high-risk foods and adventuresome eating” is the best way to sidestep this illness. But in one survey, half of afflicted vacationers admitted they didn’t follow this advice.

Remember these rules next time you venture abroad.

Sip this, not that. Drink water and other beverages from factory-sealed containers only, the American Medical Association (AMA) recommends. Beer and wine are safe. So are carbonated water and sodas. Boiled water and hot drinks like tea and coffee are usually fine according to the CDC. (At higher altitudes, experts recommend boiling water for at least three minutes.) Skip ice in drinks unless you know it was made with purified water —freezing doesn’t kill bacteria. Don’t drink tap water or brush your teeth with it.

Don’t eat like a local. The American Academy of Family Physicians (AAFP) recommends skipping food from street vendors and avoiding cut-up fruit salad, uncooked leafy greens (like lettuce and spinach) and raw or rare meat and fish. Stick with fruit and vegetables that are cooked or that you have peeled yourself. Choose restaurants that look busy and clean. “Try to avoid buffets,” the AMA advises. “Food should be recently cooked and served very hot.” Say “no thanks” to unpasteurized milk and dairy products, too.

Consider Pepto for prevention. Taking two ounces or two tablets of bismuth subsalicylate (Pepto-Bismol) four times a day during your trip could cut risk for travelers’ diarrhea by 60 percent, according to the AAFP. Traveling ‘round the world in 80 days? Skip it. CDC warns that using Pepto for longer than three weeks can cause constipation, a black tongue and ringing in the ears. Also skip if you have an aspirin allergy, kidney problems or gout or take a blood-thinner or the drug probenecid.

Pop probiotics. Stress, jet lag, diet changes and disrupted body rhythms can disturb the normally protective bacteria in the intestines and may leave you more vulnerable to bugs that cause diarrhea, a 2007 University of Washington review suggests. This report found that probiotic supplements containing Saccharomyces boulardii or a mixture of Lactobacillus acidophilus and Bifidobacterium bifidum cut the risk for travelers’ diarrhea by up to 85 percent.

Act fast if you have symptoms. It could be travelers’ diarrhea if you have three loose stools in 24 hours along with one of these symptoms: nausea, vomiting, fever, abdominal cramps, explosive gas, an urgent need to have a bowel movement or blood or mucus in your stools. Drink plenty of safe liquids and take an anti-diarrhea medicine or antibiotics if your doctor recommended or prescribed them before your trip. Get medical help for fever, blood in your stool, persistent diarrhea or vomiting and dehydration. 

Sari Harrar is an award-winning health, medicine and science journalist whose work appears in Dr. Oz The Good Life magazine, Good Housekeeping, O--Oprah Magazine, Organic Gardening and other publications.