Drug allergy to determine whether it is mild or serious method is mainly to look at the patient’s symptoms, whether the drug can be stopped in time to recover, etc. Usually mild manifestation of rash, itching and other symptoms, allergy is serious, the whole body skin showing diffuse redness, swelling and so on. 1. Mild allergy: mainly manifested as mild itching of the skin, red spots, papules, doughnut-like rash and other symptoms, which can gradually subside after stopping the drug. 2. Severe allergy: mainly manifested as dyspnea, chest tightness, palpitation, shortness of breath, pallor, decreased blood pressure, laryngeal edema, asphyxia, generalized diffuse redness, swelling and other symptoms, the symptoms can not be relieved after stopping the drug, and even threaten the patient’s life. It is recommended that after the occurrence of drug allergy, patients should go to the dermatology department of regular hospitals in time according to the situation, and be actively treated under the guidance of professional physicians, so as not to affect the adverse consequences.