The time to drink water after gastroenteroscopy should depend on the specific examination, ranging from about 2 to 72 hours. 1. Simple gastroenteroscopy: water can be drunk after the end of ordinary gastroenteroscopy; painless gastroenteroscopy, water can be drunk 2 hours after the patient is awake. 2. Microscopic histologic biopsy: If gastroscopy or colonoscopy pathologic histologic biopsy is performed, it usually takes 4~6 hours before drinking water. 3. Endoscopic treatment: such as gastric polypectomy, intestinal polypectomy and other treatments, generally need to fasting water ranging from 24 to 72 hours, the specific time should be based on the depth of the lesion, the number and operation. After doing gastroenteroscopy, it is recommended to follow the doctor’s instructions to determine the time to drink and eat, in order to avoid adverse reactions.