The Centers for Disease Control and Prevention estimates that traveler's diarrhea (T.D.) strikes up to 50 percent of visitors to "high-risk" destinations, including Mexico and India. Those who don't religiously avoid street food, tap water, and raw produce—or who can't get controversial preventive doses of Cipro—have traditionally treated "Montezuma's revenge" with over-the-counter remedies like Pepto-Bismol or Imodium.
Finally, a better choice may be around the corner: this spring the FDA is expected to approve the antibiotic Rifaximin for treatment of T.D. Rifaximin, which has been available in Italy for more than a decade and in Mexico for three years, has been shown in studies to both alleviate symptoms and shorten the duration of T.D.
Unlike Cipro, Rifaximin is a site-specific antibiotic; it remains in the gut to battle the microbes (such as E. coli) that cause diarrhea, destroying fewer beneficial bacteria in the process. A minuscule amount of the drug enters the bloodstream, lessening the chance that pathogens will mutate and adapt to it—good news given the growing incidence of antibiotic resistance. If approved in the States, Rifaximin will be available this summer, by prescription only. It is likely to be sold under the name Lumestat.