Antihistamines are a class of drugs that can compete with histamine for histamine receptors on cells, so that histamine cannot bind to receptors, thus producing antihistamine effects. According to different types of histamine receptors, antihistamines can be divided into H1 receptor blockers and H2 receptor blockers. H1 receptor blockers are commonly referred to as antihistamines in the past. It can antagonize the vasodilator and smooth muscle action of histamine and help relieve or eliminate allergy symptoms caused by endogenous histamine release. It is mainly used for the prevention and treatment of cutaneous mucous membrane allergic diseases, motion sickness and vomiting. Ebustin, cetirizine hydrochloride, loratadine, levocetirizine, and imidazolastine are several commonly used anti-H1-receptor antihistamines without sedative effect, belonging to antiallergic drugs. They are characterized by no sedative effect or little sedative effect on the central nervous system, but stronger antihistamine effect, which can significantly inhibit the red and wind clusters caused by histamine. It did not affect the release of histamine by mast cells. This product takes effect 1 to 4 hours after oral administration and peaks in blood concentration 3 to 6 hours. It can pass the blood-brain barrier and is converted to the active form carebastine in vivo. In healthy Chemicalbook adult volunteers, after one po of ebastine, Tmax is about 3 ~ 6h, and 3 ~ 5 times /d, the blood concentration can reach a stable state. The Cmax after a single dose of 10mg is about 0.1mg/L. Taking it with food increases its bioavailability. PPB is about 98%. Vd is about 90 ~ 140L. The final T1/2 was 13 ~ 16h and was mainly excreted from the urine. Clinical treatment of various allergic diseases, such as chronic idiopathic urticaria, seasonal, perennial allergic rhinitis, skin pruritus. Adults for chronic urticaria or allergic rhinitis, po, 10mg, qd; The dosage for children is 5mg, qd. High dose epasteine 20mg, qd is only used in adults with more severe allergic disease, and will be better taken in the morning. The most common adverse reactions were drowsiness, headache, dry mouth, and mild to moderate reactions in most patients, which did not affect the continuation of medication. Other rare adverse reactions include fatigue, nausea, vomiting, hyperappetite, diarrhea, constipation, and restlessness. The most common adverse reactions were headache and gastrointestinal disorder.