Drinking water in the morning is not recommended for stomach examinations. Gastroscopy and urea breath test need to be done on an empty stomach, and drinking water may affect the results or aggravate adverse reactions such as vomiting. Gastroscopy needs to be done on a completely empty stomach, which means that you need to fast and abstain from food and water for 6 to 8 hours before undergoing a gastroscopy. Gastroscopy is a comprehensive observation of the stomach. If you eat or drink before having a gastroscopy, it may lead to an increase in stomach contents, blocking the doctor’s view of the examination, which may cause the doctor to not see the lesions in the stomach clearly, affecting the results of the guided examination. Gastroscopy is a method of examination in which a thin, flexible tube with a camera (endoscope) is inserted into the stomach and the mucous membranes of the esophagus, stomach, and duodenum are viewed sequentially through the endoscope. Gastroscopy is not recommended for patients with serious heart, liver, or lung disease, and it is important to listen to your doctor’s advice as to whether or not gastroscopy is needed and can be performed. The 13C and 14C urea breath test also requires fasting.