Cimetidine, also known as mecamidine, has a significant inhibitory effect on gastric acid secretion, which can significantly inhibit basal and nocturnal gastric acid secretion, and also inhibit gastric acid secretion caused by histamine secretion gastrin, insulin and food stimulation, and make it less acidic, and has a preventive and protective effect on corrosive gastritis caused by chemical stimulation. It also has a significant effect on irritated gastric ulcers and upper gastrointestinal bleeding, and is used for the treatment of duodenal ulcers, gastric ulcers, upper gastrointestinal bleeding, chronic colitis, herpes zoster, chronic urticaria and other symptoms, and is useful for anti-viral as well as immune enhancement.