Drug allergy usually refers to the patient with some drugs, the symptoms of allergy, and drug allergy a few days can be exhausted, and the half-life of the drug is related to the general need for 1-2 weeks to exhaust, the specific also need to be based on the type of drugs used by the patient, the amount of drugs, and the individual physique to decide. Drugs need to be metabolized by the body, the metabolism is affected by the half-life of the drug, each drug has a different half-life, the longer the half-life, the longer the metabolism. On the contrary, the shorter the half-life of the drug, the shorter the metabolism time, most of them can be eliminated in 1-2 weeks. However, if the patient is elderly or suffers from some kind of disease, resulting in blood circulation disorders, poor circulation of the body, and the drug is taken in large doses, resulting in severe allergic reactions, the time required for the drug to be exhausted will be correspondingly prolonged. After the drug allergy, the patient can under the guidance of the doctor through intravenous drip anti-allergy drugs, or infusion to promote the body’s metabolism, so that the allergy after the residual drugs in the body faster removal. In addition, you can also accelerate the metabolism through dietary modification, such as drinking more water, eating light, high protein food, try to quit smoking, alcohol, spicy and irritating food, etc., to accelerate the body’s residual drug discharge. Patients should pay attention to avoid contact with allergens as much as possible, and do drug sensitivity test in advance when using drugs that are easy to be allergic to. If patients experience weakness, chest tightness, drowsiness, etc. after using the drugs, it is recommended to seek medical attention in time.