Chlorpheniramine is used for allergic rhinitis, cold and sinusitis and allergic skin disorders such as urticaria, allergic drug rash or eczema, angioneurotic edema, and itchy skin caused by insect bites. Indications for cold and skin mucosal allergic diseases, functions for urticaria, eczema, dermatitis, drug rash, pruritus, neurodermatitis, insect bite, solar dermatitis, can also be used for allergic dermatitis, vasomotor rhinitis, drug and food allergies. In addition to the competitive blocking effect of histamine H1 receptor on the target cells of allergy reaction, through the antagonism of H1 receptor, it also has the effect of anti-M choline receptor, so after taking the drug, dry mouth, constipation, sputum thickening, dry nasal mucosa and other symptoms.