The most serious hypersensitivity reaction caused by penicillin is anaphylaxis. In people who are allergic to penicillin, exposure to penicillin usually results in a rapid onset of the disease, leading to a systemic anaphylactic reaction that is characterized by acute peripheral circulatory underperfusion. In addition to causing shock symptoms such as decreased blood pressure, chest tightness, palpitations, and pallor, it is often accompanied by laryngeal edema, tracheal spasm, and pulmonary edema, and may even lead to death. And those who are highly allergic to penicillin may cause anaphylactic shock with only a small amount of penicillin exposure, which can be life-threatening. Once anaphylactic shock occurs, it should be resuscitated immediately by stopping penicillin infusion and tying a tourniquet around the proximal end of the injection site, and relaxing the tourniquet every 15-20 minutes according to the condition of the patient to prevent ischemic necrosis of the tissues. At the same time, immediately let the patient take the lying position, loosen the collar and pants buckle. If the patient has respiratory difficulties, the upper body can be raised appropriately. If the patient loses consciousness, the head should be placed in the lateral position and the lower jaw should be lifted to prevent the tongue from falling back and blocking the airway. At the same time, remove oral, nasal, pharyngeal and tracheal secretions, clear the airway, and administer high-flow oxygen by mask or nasal cannula. In the presence of severe laryngeal edema, tracheotomy is required, and for severe and unrelieved tracheospasm, tracheal intubation and assisted breathing are sometimes required. In addition, immediate intramuscular injection of epinephrine should be given, and two intravenous channels should be opened at the same time, with the use of dexamethasone, methylprednisolone and other medications to treat, and actively replenish blood volume. Cardiopulmonary resuscitation can also be performed in case of cardiac arrest. Therefore, before using penicillin, it is necessary to inform the doctor whether there is a history of allergy, and those with a history of allergy should be treated with other drugs instead, and those without a history of allergy also need to carry out skin tests. The skin test is also required for those without a history of allergy and for different routes of administration such as oral, intravenous or intramuscular.