The main effect of diphenhydramine hydrochloride is to eliminate various allergic symptoms, the role of central inhibition is more obvious, but not as good as promethazine hydrochloride, and this drug has a sedative, anti-motion sickness and antiemetic effect, also has an anticholinergic effect, can relieve bronchial smooth muscle spasm, for a variety of allergic skin diseases, such as urticaria, insect bites, can also be used for motion sickness, nausea and vomiting. Adverse drug reactions include: i. Common central depressive effects, such as drowsiness, dizziness, headache, dry mouth, nausea, vomiting and epigastric discomfort. Second, rare adverse reactions include shortness of breath, chest tightness, cough, dystonia, etc. It has been reported that tooth closure with laryngospasm can occur after the administration of the drug. Third, the elderly are prone to prolonged sluggishness or dizziness after drug administration. Dosage and administration are oral, 25-50 mg per dose for adults, 2-3 times daily. For children, 2-3 times daily: under 1 year old, 2.5mg-5mg each time; 1-3 years old, 5mg-7.5mg each time; 4-6 years old, 7.5mg-10mg each time; over 7 years old, 10mg-12.5mg once.