Mouth ulcers if it is due to gastrointestinal mucosal ulcers caused by bacterial infection induced, with ranitidine can have a certain effect, other etiology caused by mouth ulcers eat ranitidine has no effect, it is recommended to the hospital specific examination and treatment. 1. Ranitidine is mainly a drug that inhibits gastric acid and has a therapeutic effect on gastric mucosal ulcers and duodenal ulcers. 2. Flora disorders caused by gastrointestinal mucosal diseases may affect the flora disorders in the oral cavity, which may lead to oral mucosal ulcers, and this kind of oral ulcers has a role with Ranitidine. Due to mechanical injury, viral infection, vitamin deficiency and other causes of oral ulcers, eat Ranitidine is basically no effect, it is recommended that oral ulcers to the hospital examination and treatment, the use of drugs need to comply with medical advice.