Drug allergy can cause a variety of systemic or local symptoms 1, drug rash, such as fixed erythema, erythematous eruption, etc., dominate in drug allergy. 2, anaphylaxis: this is a serious and critical drug allergic reaction, often manifested as respiratory distress, blood circulation failure and coma, etc., sometimes life-threatening. The anaphylaxis caused by penicillin must not be unfamiliar to everyone. 3, induced aggravation of asthma. 4.Hematological disease-like reaction: It is the abnormality of blood system caused by drugs, including granulocytopenia or deficiency, aplastic anemia and thrombocytopenia, etc. 5.Seropathy-like reactions: usually manifest as fever, joint swelling and pain, “rubella” on the skin, swollen lymph nodes, and sometimes myocardial damage, etc. 6, hepatitis-like reactions: most of the manifestations of gangrene, liver dysfunction, transaminases elevated, often accompanied by fever and rash, most of the disease can be reversed, severe cases can develop into acute liver necrosis. 7. 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 manifestations, it is difficult to identify for a while. 8, other, damage to some important organs such as the heart, kidneys and central nervous system, can also involve the eyes and ears and other important organs.