Cimetidine injection is a drug that inhibits gastric acid secretion, which works by inhibiting H2 receptor blockers on gastric wall cells, and treats diseases related to excessive gastric acid secretion by reducing gastric acid secretion, such as gastritis, gastric erosion, gastric ulcer, duodenal ulcer and reflux esophagitis. For example, there are ranitidine, famotidine, nizatidine, etc., and the effect of treatment can be achieved in 3 days of medication in general. In addition, because of the side effects of this drug, it has been gradually replaced in the clinic by proton pump inhibitors, such as omeprazole and lansoprazole.