How to Avoid Montezuma’s Revenge

When the local fare is too much for your digestive system.

Montezuma’s revenge, Delhi belly, turista—by any name it’s traveler’s diarrhea, and though it mostly afflicts visitors to developing countries, it can strike anywhere. Contaminated water, poor sewage treatment, or unsanitary food handling can allow parasites and E. coli to enter the food supply. According to the World Health Organization (WHO), millions of people become ill and thousands die every day from food-borne diseases. “If you go anywhere beyond the occasional business meeting in London, you’re going to get this,” says Alan J. Magill, M.D.

The standard guideline for food safety is boil it, peel it, or forget it. Boiling is by far the most reliable way to make water safe for drinking, but it’s hardly practical. Another method is to treat water with iodine tablets for a minimum of 30 minutes before drinking it. Using a reverse-osmosis water filter is also an option, but make sure it is fine enough to be effective. The nonprofit organization NSF International compares specific models on its Web site (

“If you drink a carbonated beverage, you can be reasonably certain that it was bottled in a plant,” says Bradley Connor, M.D. “But milk or fruit juice can be contaminated because they’re often diluted with water.” The WHO recommends avoiding any uncooked foods except for fruits and vegetables peeled yourself; anything made with raw or undercooked eggs, such as homemade mayonnaise or Caesar salad; and buffets or street-food stalls where raw and cooked food may come into contact with each other. “Even in five-star hotels, there are factors outside our control,” says Connor. “Generally, anything freshly prepared and served hot is best.”

There’s an 80 percent chance that any traveler’s diarrhea is bacterial, so you may want to carry the antibiotic ciprofloxacin—though in Southeast Asia it’s better to have azithromycin (brand name Zithromax). “Historically, Americans have favored using antibiotics quickly and liberally, but the European attitude is ‘Just rest and take fluids,’ ” says Magill. “It’s true, you will get better with rest, but that’s not why people travel. An anti-motility agent such as loperamide, better known as Imodium, can come in handy on a long bus ride.”

Replacing lost fluids and electrolytes is an important part of treating diarrhea. The American Society of Tropical Medicine and Hygiene recommends commercial rehydration salts, like CeraLyte, or a home brew made by mixing a teaspoon of salt and two or three tablespoons of sugar into a liter of potable water.

Until recently the pharmaceutical industry only offered treatment, not prevention, of traveler’s diarrhea, but that’s changing. The Annals of Internal Medicine published a study in 2005 in which more than 200 students arriving in Guadalajara, Mexico, were given a drug called rifaximin (brand name Xifaxan, sold in Europe as Spiraxin or Zaxine). Only 14 percent developed traveler’s diarrhea, as opposed to 53 percent of those who took a placebo. But Herbert L. DuPont, M.D., director of the University of Texas’s Center for Infectious Diseases, who conducted the trial, notes that more study is needed, especially in Asia.

Another possible preventive is Travelan, an over-the-counter pill containing antibodies from bovine colostrum, a fluid in milk that provides newborn calves with immunity to infections. Travelan is not regulated by the FDA, but its manufacturer claims it prevents bacteria from binding to the small intestine. One minor bovine colostrum study done with 20 volunteers in 1988 had positive results, but no research seems to have been published since. The anti-cholera vaccine Dukoral was found to have some cross-protection against other bacterial toxins, including those that cause traveler’s diarrhea, but it’s not FDA-approved for any use in this country.

Stay tuned, though: Later this year 1,800 subjects from the United States and Europe will be given an as-yet-unnamed vaccine patch, produced by the Austrian biotech firm Intercell, before traveling to Mexico or Guatemala, and monitored to see if they stave off Montezuma’s revenge.

“None of these things is going to be 100 percent effective,” warns James M. Fleckenstein, M.D., a vaccine researcher at the University of Tennessee’s Health Science Center. “As long as bacteria contain toxins, they can transmit disease. Avoidance is still the best way to prevent illness.”


The antibiotic ciprofloxacin, sold under the names Cipro and Ciloxan, is prescribed to fight bacterial toxins from contaminated food and water.

Boil it, peel it, or forget it. When it comes to fruits and vegetables, eat only those you peel with your own (clean) hands, like bananas and oranges.