The most common health problems facing travelers in Asia are diarrhea and dysentery. Often given graphic names like "Delhi belly" and the "Kathmandu Quick-step", these chronic intestinal disorders are usually caused by ingesting food or water contaminated by certain pathogenic microorganisms originating from human or animal feces. Because sewage disposal and food preparation in Asia are not always up to Western standards, a few precautions regarding personal hygiene and what you eat or drink can help reduce the chances of getting diarrhea.

Wash your hands often with soap, especially before meals, and don't lick your fingers or use them as a toothpick. Drink only water that has been boiled properly or purified wit a form of iodine; this includes the tap water in Lhasa. The Tibetans and Chinese rarely drink water that hasn't been boiled first; their example is a good one to follow. Fresh fruits and vegetables should be peeled or washed in sanitary conditions before they are eaten.

Avoid food in restaurants that obviously has been sitting out for a long time or has been exposed to flies.

Most Chinese and Tibetan hotels and guest houses provide a thermos in every room containing safe, boiled water. Chhang, the popular homemade Tibetan beer, is made by mixing fermented barley berries with water, but the water may not have been boiled first. Butter tea and araa, a distilled clear alcohol, are safe because they have been boiled, but the cup or bowl it's served in could be your downfall. The intestinal infections that cause diarrhea in travelers are usually self-limiting and often go away on their own within two days to a week. For most people, this is too long to wait. The best course is to identify the intruding microorganism by means of a laboratory stool test, then take an appropriate antibiotic, but if you are on a trek the only choice is to know the evidence of your symptoms and make an educated guess regarding the proper treatment. Most cases of diarrhea fall into one of three categories; simple diarrhea, dysentery, or persistent diarrhea.