The severity of fever of 39℃ is related to the patient’s age, vital signs, symptoms and other specific circumstances, and timely consultation is recommended. If the fever of 39 ℃ when the patient’s mental, physical and other general conditions are still good, the condition is usually not too serious, can be given ibuprofen suspension, diclofenac sodium suppositories to lower the temperature, and for the original disease of anti-infection or related treatment. If the patient has a high fever with symptoms such as impaired consciousness, dyspnea, hypotension, etc., especially in patients of advanced age, debilitated, and with multiple underlying diseases, the condition is usually serious and the prognosis is poor, and the patient needs to be actively treated to maintain vital signs. Fever is a common symptom, which can be caused by various infections, blood diseases, autoimmune diseases, tumors, etc. The specific severity of the disease must be assessed by the physician, and it is recommended that patients consult a doctor in a timely manner in order to avoid delaying their condition.