Many patients and their families do not understand that they cannot eat or drink before surgery, and some patients and parents are afraid of aggravating themselves and their children, and some even believe that they need to eat well before surgery to better “tolerate surgery”, and that “surgery on a hungry stomach is unbearable “. As a result, sometimes patients or family members have to stop the operation and do it again at a later date because they did not listen to the physician’s advice or forgot the nurse’s instructions and ate before the operation. Gastrointestinal preparation is an important part of preoperative preparation, which is mainly to prevent asphyxia or aspiration pneumonia due to vomiting reaction during anesthesia or surgery. And this vomiting reaction may occur at any time during anesthesia, especially during tracheal intubation, suction tube aspiration and catheter removal, because some anesthetic drugs attenuate the body’s normal protective reflexes. For example, the lungs have protective cough reflexes to stomach contents to prevent them from entering the lungs, but after anesthesia, these reflexes disappear. Stomach acid is very irritating to the lungs, and once it enters the lungs it often causes aspiration pneumonia, which can lead to respiratory failure and affect life. If anesthesia surgery is performed after eating or drinking a lot of water, the stomach contents can be regurgitated before digestion into the intestine, which will not only affect the normal operation, but also may cause serious complications and threaten the patient’s life. So when can you not eat or drink before surgery? It depends on the site, type and size of the surgery and the patient’s age and general condition, etc. In general, eating and drinking should be prohibited 12 hours before surgery and from 4 hours onwards. In our hospital, for general plastic surgery, adults are routinely asked to start fasting after dinner the day before surgery, and after a cleansing enema, they can drink 250-500ml of plain water or sugar water before bedtime, but they must not consume any other highly nutritious drinks or solid foods. It is important to emphasize here that dairy foods are not beverages, but rather solid foods because they take longer to be digested in the stomach. On the day of surgery, if it is the first surgery, do not drink water or eat any food after waking up in the morning; if it is the next surgery, drink a small amount of plain water or sugar water before 4 hours before the surgery. For pediatric patients, diet (including dairy foods) is routinely prohibited 6 hours prior to surgery, and drinking is prohibited from 3 hours onwards.