Total epidermal necrosis and subepidermal macules are one of the symptoms of toxic necrotizing epidermolysis bullosa drug rash. Most drugs have the potential to cause drug rash, including herbal medicines, but those with stronger antigenicity cause the most. Most of them are sulfonamides, salicylates, antipyretic and analgesic drugs such as pautazone and aminopyrine, phenolphthalein, penicillin, tetracycline, barbiturate, phenytoin sodium, etc. In addition, the risk of drug rash is higher in organisms with congenital allergic diseases and in patients with diseases of vital organs. Toxic necrotizing epidermolysis bullosa (TEN) is the most severe form of drug rash and is usually seen first in the emergency department. Drug rash is a medical condition, so care must be taken to: 1. Ask the patient what kind of allergy history he has before using the drug, and avoid using drugs with known allergies or similar structures. 2. 2. The medication should be targeted, and less allergenic drugs should be used as much as possible. The early symptoms of drug rash should be noted during treatment, such as the sudden appearance of itching, erythema, fever and other reactions, the suspected drug should be immediately stopped, closely observed and strive to identify the allergenic drugs. 3, the application of penicillin, serum, procaine and other drugs should be made in accordance with the prescribed method of skin testing, positive can not be treated with the drug. Before the skin test, emergency drugs should be available to meet the urgent needs. The current national concentration of skin test solution is penicillin 500u/ml, streptomycin 5mg/m1, procaine 0,25%, tetanus antitoxin 1:10, the dosage is 0,1m1. 4, has been diagnosed as drug rash, the allergenic drugs should be recorded in the medical record and asked the patient to remember, every time you visit the doctor should tell the doctor not to use the drug.