Each year, an estimated 10 million international travelers get traveler's diarrhea, according to the Centers for Disease Control and Prevention (CDC). The illness is usually caused by bacteria and typically leads to bloating, abdominal cramps, and frequent diarrhea. To avoid getting it "drink only bottled water, avoid eating foods from street vendors, and don't eat raw fruits or vegetables—even on the plane—unless you can peel them yourself," Dr. Yoshida advises. If you do get sick, rest assured: Traveler's diarrhea usually lasts only a day or two. In the meantime, drink lots of water and Gatorade or buy oral rehydration packets you can mix with bottled water. If you develop bloody diarrhea, a fever, or you get weak or dehydrated, see a doctor because you may need antibiotics, Dr. Yoshida says.