Many diseases require medications to treat them, but certain medications can also cause a skin condition, known as drug rash, in people with allergies. Drug rash, also known as drug dermatitis, is a skin and mucous membrane reaction caused by drugs entering the body through injection, internal administration, inhalation, etc. It is the most common type of adverse drug reaction. In recent years, with the increasing variety and application of new drugs, the incidence of drug rash has also been increasing year by year. The manifestations of drug rash are diverse, and in mild cases, there can be only erythema, itching and other skin discomfort symptoms; in severe cases, it can cause generalized epidermal peeling or necrosis, extensive mucosal erosion, and systemic damage, leading to death or survival leaving a variety of sequelae such as blindness. Therefore, it is necessary to be alert to the occurrence of drug rash when using drugs, and once it appears, it should be promptly diagnosed and treated without delay. Any drug can cause drug rash under certain conditions, but whether it causes drug rash also depends on individual factors, drug factors and infection factors. The drugs that often cause drug rash are: antibiotics such as penicillin, cephalosporins, sulfonamides, etc.; antipyretic and analgesic drugs; hypnotic, sedative and antiepileptic drugs that act on the central nervous system; antigout drugs such as allopurinol; allogeneic serum preparations and vaccines and herbal medicines. Most drug rashes are caused by allergic reactions (hypersensitivity reactions). Generally speaking, there are some characteristics of allergic drug rash as follows: ① Only a small number of allergic drug users, while most people do not react; ② The severity of the disease does not correlate with the pharmacological and toxicological effects of the drug, the dose; hypersensitivity, even very small doses of drugs can lead to very serious drug rash; ③ The onset of a certain latency period, the initial use of drugs generally takes about 4 -The clinical manifestations are complex, and the lesions can be of various types, but for a particular patient, one is often the main one. According to the shape of the lesions, drug rash can be divided into fixed, urticarial, eruptive, eczema, purpura, acne, photosensitive, erythema multiforme, epidermolysis bullosa, exfoliative dermatitis, drug hypersensitivity syndrome and other types. Among them, severe erythema multiforme, herpetic epidermolysis bullosa, exfoliative dermatitis and drug hypersensitivity syndrome are serious and have a high mortality rate. Because drug rash is a drug-derived disease, prevention is particularly important. 1. Clinical drug use should avoid drug abuse and minimize the variety of drugs used; for known allergenic drugs, they should be noted on the medical record card to avoid reuse; physicians should ask for detailed drug allergy history before prescribing and try to avoid reuse of such drugs or drugs with similar structure to avoid cross-allergy; 2. Patients should also keep in mind the allergic drugs and take the initiative to provide physicians with past drug allergy history; 3. 3. Before the occurrence of drug rash, there are often some precursor symptoms. If itching, skin redness, fever and general malaise occur after the drug is used, the patient should seek medical consultation in time to find the allergenic drug and discontinue it to avoid serious adverse reactions; 4. Once the drug rash occurs, first of all, all suspected allergenic drugs should be discontinued; at the same time, drink more water to accelerate the excretion of drugs, and under the guidance of a physician to clarify the allergenic drugs and take appropriate treatment; for heavy drug rash and urticaria-type drug rash with abdominal pain or shock must be hospitalized. So drug rash still has to be treated by medication, including internal and external use, and even resuscitation.