Drug rashes, or drug dermatitis, include fixed-type drug rashes, urticaria-type drug rashes, and measles-type or scarlet fever-type drug rashes. Different types of drug rashes also appear in different places. 1. Fixed drug rash: often caused by antipyretic analgesics, sulfonamides, barbiturates and tetracyclines. It occurs in the skin-mucous membrane junction of the oral cavity and genitals, and occasionally involves the trunk and limbs, manifesting itself as a similar rash in almost the same place every time. 2. Urticaria-type drug rash: tetanus antitoxin, furazolidone and other drugs cause the most common. Caused by the mechanism of hypersensitivity reaction and non-hypersensitivity reaction mechanism. Clinical manifestations are similar to acute urticaria, manifested as erythema, flaky masses, itching is more obvious, can appear in the whole body. 3. Measles or scarlet fever drug rash: common in patients using penicillin, isoamylbarbitone, secobarbital and other drugs. Due to the toxicological effect of drugs appear skin lesions, for the pinhead or millet size of the red papules, symmetrical distribution, can be all over the body, especially the trunk. When the appearance of drug rash, it is recommended to promptly seek medical attention, follow the doctor’s instructions for further examination, with the help of the doctor to clarify the cause, targeted treatment or therapy.