How long to use cimetidine injection usually depends on the degree of relief of the patient’s symptoms, usually if there is no stomach pain, acid reflux, heartburn and other symptoms, then the drug can be discontinued and replaced by oral preparations. Cimetidine injection belongs to the histamine H2 receptor antagonist, can inhibit the secretion of gastric acid, usually used to treat gastric ulcer, duodenal ulcer and other diseases, the specific dosage and duration of treatment should be determined by the doctor according to the patient’s condition. For cimetidine allergy, pregnant and lactating women are prohibited, severe hepatic and renal insufficiency and severe cardiac disease patients with caution. Caffeine and caffeine-containing beverages are also prohibited during the medication period. When it comes to the use of medication, it is necessary to strictly follow the instructions of the doctor, and it is recommended that the patient first consult a doctor for examination, and the specific course of treatment should be formulated by the doctor according to the patient’s diagnosis.