Fever in adults should not last more than a few days, depending on the degree of fever, the progress of the disease and the resistance of the patient. Fever is caused by external pathogens or other stimuli and is a self-protection mechanism of the body’s immunity. A short-term increase in body temperature is conducive to the body to kill pathogens and the toxins produced by pathogens, while a prolonged fever will affect the body’s metabolism, and even damage tissues and organs. If the patient has strong resistance and low fever, even if the fever is 1 week, it will not cause complications. If the patient has a high fever, is usually in poor health and is not treated, the fever may cause complications such as pneumonia and lung abscess for 3 consecutive days. Therefore, if the patient’s temperature is elevated when measured with a thermometer, measures should be taken to lower the temperature, and should not be allowed to develop freely, in order to avoid causing serious complications.