Total epidermal necrosis and subepidermal macules are one of the symptoms of toxic necrotizing epidermolysis bullosa drug rash. The adverse reaction of skin and/or mucosal damage caused by drugs used for prophylaxis, diagnosis, and treatment, regardless of the route of entry into the organism, is called drug rash. It is a common condition in dermatological emergencies. Toxic epidermal necrotizing drug rash is a serious skin disease with multisystem damage. It is characterized by a large area of damage and a high mortality rate. The prevention of drug rash should pay attention to the following matters: 1, the use of drugs must be careful, do not abuse. If an unexplained erythematous papular rash or generalized itchy skin occurs during the use of medication, it should be seen as a “yellow alert”, which may be an early manifestation of drug rash. If the situation allows, the drug can be discontinued in time and take positive measures, most patients have a good prognosis, do not continue to use the drug after the emergence of allergic reactions. 2. Pay attention to the accumulation of life, summarize in a timely manner to which drugs they have allergies, establish a drug allergy card, and explain to the doctor that the use of a certain drug is prohibited when you go to the doctor. Once a patient is clearly allergic to a certain drug, he or she can no longer use that drug or drugs with similar chemical structures; he or she cannot abuse the drug privately, and should follow the doctor’s instructions to do skin allergy tests as required. 3, the patient has a cold, fever, abdominal pain, diarrhea, medication, especially careful, can use a drug, do not use two, can not use the drug is best not to use. This is because antibacterial and anti-inflammatory drugs and antipyretic drugs have the most frequent chance of allergy. 4, after the occurrence of drug rash, should drink more water, when possible infusion therapy to promote the excretion of drugs in the body. Eat less spicy and irritating food (such as chili, garlic, wine, coffee, shrimp, crab, scallops and other seafood). Eat foods that are high in calories, protein, vitamins and easy to digest and absorb (such as chicken, eggs, milk, lean meat, river fish, fresh fruits and vegetables), preferably cooked and stewed. But for the usually allergy-prone foods, such as mangoes, peaches, pears, lychees, longan, nuts, buckwheat, etc. to be very careful, it is best not to eat first. 5, pay attention to keep your mouth clean and hygienic, before and after meals with saline rinse and brush your teeth. 6, drug rash first healed, the body resistance is low. You should not exert yourself, rest more, should not do physical exercise, and should not go to crowded and noisy public places. 7, once the anaphylaxis occurs, should be every second, immediately discontinue, remove allergy-causing drugs, closely observe vital signs, active resuscitation, do not move around.