The duration of fever cannot be determined and depends mainly on the patient’s condition and treatment. Fever is a common clinical symptom that can be caused by a variety of diseases, such as bacterial, viral, parasitic and other pathogenic infections, autoimmune diseases, malignant tumors, etc. Fever symptoms can occur. The duration of fever is related to the disease, the patient’s resistance and the treatment method. For example, fever symptoms can disappear after 3-5 days of anti-infection treatment for various types of infections caused by bacterial and viral infections. In case of improper treatment, drug resistance of the causative bacteria, etc., fever can last for 1 week or even longer. The symptoms of fever should firstly be active to clarify the cause, if the body temperature is high, antipyretic treatment can be taken: if the body temperature is below 38.5℃, physical cooling can be taken, over 38.5℃, drug treatment can be taken. At the same time, drink more water, pay attention to rest and eat lightly.