Whether an allergy is life-threatening to the patient should be differentiated according to the severity of the allergy. If the patient has only a mild skin allergy, the prognosis is mostly good. Patients with severe allergies, such as penicillin allergy, require immediate resuscitation or else their lives may be threatened. When the body comes into contact with a substance and recognizes it as harmful, the body activates the immune system, which immediately responds to repel or destroy the substance, which is called the immune response and can play a protective role. The immune response is one of the most important functions of the human body. If the response exceeds the normal range and causes the immune system to attack harmless substances, it is called an allergic reaction, which leads to diseases such as hives and allergic rhinitis. After standardized treatment and avoiding contact with allergic substances, most of them have a good prognosis. However, if anaphylaxis is caused by penicillin or other sensitizing factors, immediate rescue treatment is needed. At this time, the course of the disease progresses rapidly, and failure to save the patient’s life can threaten the safety of the patient within a few minutes. If allergy occurs, the patient should go to the allergy department of the hospital, do allergen test, determine the allergen, then symptomatic treatment, and avoid contact in daily life.