Acute gastritis is an acute inflammation of the gastric mucosa caused by no etiology. Clinically, it can be divided into acute suppurative gastritis, acute erosive gastritis, acute simple gastritis, and acute corrosive gastritis, with simple gastritis being the most common. Some people divide it into two categories: acute exogenous and acute endogenous. Any gastritis caused by pathogenic factors entering the stomach through the mouth is called exogenous gastritis, including bacterial gastritis, toxic gastritis, corrosive gastritis, drug-induced gastritis, etc.; any gastritis caused by harmful factors reaching the gastric mucosa through the blood circulation is called endogenous gastritis, including acute infectious diseases combined with gastritis, systemic diseases (such as uremia, cirrhosis, cor pulmonale, respiratory failure, etc.) combined with gastritis, suppurative gastritis, allergic gastritis, and irritable lesions. In recent years, due to the widespread use of endoscopy, it has been found that stress lesions are very common and are one of the common causes of acute upper gastrointestinal bleeding.