Acid heartburn is a clinical condition in which the cells of the stomach lining secrete too much gastric acid, irritating the gastric mucosal cells and causing a burning-like discomfort in the upper abdomen of the stomach. Acid heartburn is a common symptom of gastric disorders and can be caused by certain physiological factors or by diseases such as peptic ulcer, chronic gastritis and reflux esophagitis. Some physiological factors can cause acid heartburn, such as prolonged satiety, especially with high-fat foods. The pressure in the stomach increases after satiety, and high-fat food passing through the digestive organs can promote the secretion of some gastrointestinal hormones, which have the effect of relaxing the lower esophageal sphincter, thus causing stomach acid to reflux easily into the esophagus. This is also true for long-term smokers and alcohol drinkers, and foods such as coffee and chocolate can cause a similar situation. In addition to physiological factors, certain diseases can also cause acid heartburn, such as peptic ulcer, chronic gastritis, gastroesophageal reflux, etc. Since normal gastric juice is acidic, the stomach is protected by mucous membrane from damage by gastric acid, while the esophagus is not. Therefore, in gastroesophageal reflux, stomach acid refluxes into the esophagus, destroying the normal mucosa in the esophagus, and acid heartburn symptoms appear. People with chronic gastritis often experience varying degrees of acid reflux and heartburn discomfort, and in severe cases, abdominal pain. In conclusion, many diseases of the digestive system can cause clinical symptoms of acid heartburn, so it is important to improve the relevant tests for proper diagnosis and to provide appropriate medication to avoid possible complications.