Drug rash, or drug dermatitis, is a drug reaction manifested mainly by a rash on the skin and mucous membranes, and it is a major component of drug allergy. And drug allergy, in addition to drug rash also includes the following kinds of systemic allergic reactions. 1, anaphylaxis: this is a serious and critical drug allergic reaction, often manifested as respiratory distress, blood circulation failure and coma, sometimes life-threatening. The anaphylactic shock caused by penicillin must not be unfamiliar to you. 2, hematologic-like reactions: are drug-induced abnormalities of the blood system, including granulocytopenia or deficiency, aplastic anemia and thrombocytopenia. 3.Seropathy-like reactions: usually manifest as fever, joint swelling and pain, “rubella” on the skin, swollen lymph nodes, and sometimes heart muscle damage. 4, hepatitis-like reactions: most of the manifestations are jaundice, liver dysfunction, elevated transaminases (ALT), often accompanied by fever and rash, most of the disease can be reversed, severe cases can develop into acute hepatic necrosis. 5. Drug fever: It is a fever caused by drug reaction, and in many cases it is the only systemic symptom. Sometimes only fever exists without rash, and it is difficult to identify it for a while. 6. Other reactions: Drug allergy may also cause asthma, induce or aggravate lupus erythematosus, or damage some important organs such as heart, kidney and central nervous system, and may also involve important organs such as eyes and ears. In short, drug allergy can cause a wide variety of systemic or local symptoms. Of course, it is the drug rash that dominates drug allergy, and it is worth mentioning that the latter, in a few cases, has the involvement of some other factors that make its manifestation more complex. In mild cases, drug allergic reactions may cause dysfunction of various organs, manifesting as rash, asthma, fever and other symptoms; in severe cases, shock may occur, even life-threatening. In case of allergic reactions, stopping the medication is only the primary measure, but at the same time, observation should be strengthened and symptomatic treatment should be given according to the condition. Those with mild symptoms should drink more water to speed up the discharge of drugs. If necessary, oral anti-allergic drugs or large amounts of fluids should be administered under the guidance of a doctor to speed up the discharge of residual drugs and prevent the allergic person’s lesion from becoming a fatal exfoliative dermatitis or multiple organ damage and death. If the allergy is caused by the combination of multiple drugs, it is difficult to distinguish which drug is causing the allergy for a while, and all of them should be stopped. At the same time, adjust the treatment according to the symptoms of allergy, or take measures such as gastric lavage and enema to make the drug excreted or block the absorption of the drug as soon as possible.