There are many reasons for the itchy skin rash, common causes may be allergic skin diseases, mosquito bites, viral skin diseases, etc., according to the cause of the choice of topical or oral medication. 1. Metabolic skin disease: various causes such as diet, environment, season, drugs, etc. through a variety of ways into the body leading to abnormal immune response, and triggered a series of skin diseases, common eczema, urticaria, drug rash. (1) Eczema: clinical manifestations of erythema, papules, blisters, mossy changes and other polymorphic rashes, often symmetrical recurrence, itching is obvious. (2) Urticaria: the basic damage for the wind, manifested as the edge of the slightly elevated reddish or bright red patches, gradually expanding and fused into a piece, the boundary is clear, can be subsided within 24 hours, but recurrent episodes, accompanied by obvious itching. (3) drug rash: before the onset of a clear history of drug use, common drugs for antibiotics, sulfonamides, sedatives and antipyretic analgesics, drug rash is diverse, the performance is complex, it is recommended to take drugs recently appeared around the body erythema itchy patients, timely medical treatment, targeted treatment. 2. Mosquito bites: more mosquitoes in summer, the bite will also appear itching and red rash, generally do not need special treatment, if the itching is heavier, the rash is more, can be used externally dinexed cream, oral loratadine. There are also relatively rare such as scabies, lice disease, etc., need to physician differential diagnosis, and targeted treatment, such as topical sulfur ointment. 3. Viral skin diseases: prevalent in children, adolescents, common chickenpox, measles, rubella, often accompanied by colds, fever and other early symptoms, followed by skin rashes around the body, some may be accompanied by lymph node enlargement, at this time the need for timely medical treatment, targeted antiviral therapy and symptomatic treatment. Itchy skin rash causes complex, it is recommended to go to the hospital, a clear cause of standardized treatment, the above medication should be used under the guidance of a doctor, avoid self-medication, so as not to cause adverse consequences.