Food turning upward into the mouth after a meal is caused by indigestion, reflux esophagitis, pyloric obstruction, and other factors. When people with indigestion are overly full, the food is not digested and emptied in time, so it can also lead to excessive pressure in the stomach, and some people will have food reflux into their mouths because of excessive internal pressure. In patients with reflux esophagitis, the cardia sphincter is relaxed, especially when there is excessive secretion of gastric acid, which causes irritation to the gastric mucosa, and when the stomach spasms and contractions cause food in the stomach to reflux into the esophageal area. Some people will have pyloric obstruction, because food is digested and discharged mainly through the pylorus into the duodenum, so once the obstruction occurs food cannot be emptied. When the food in the stomach collects excessively, bad fermentation and spoilage will cause irritation to the stomach wall, resulting in excessive expansion of the stomach and increased pressure, which will then lead to reflux of food into the mouth.