Drinking water about 2 hours after gastroscopy is the best time because it is influenced by three factors: first, some patients cannot tolerate the pain of gastroscopy and need to inject anesthetic to do painless gastroscopy, because the effect of anesthetic is not immediately drink water. Second, to do ordinary gastroscopy will be pre-drinking numbing agent, then there is little pain in the throat, or will be accompanied by discomfort, immediately drink water prone to choking and coughing trachea. Third, some gastrointestinal discomfort to do gastroscopy patients in the gastroscopy process will see lesions, such as polyps, gastric erosion, are required to cut off part of the lesion to do pathological sections, so that further examination to clarify the cause, if this is the reason for two days it is best to eat light, easy to digest food.