Often, I see online inquiries like, “I’ve had a fever for a few days and fluids, why do I still have a fever?” There is no relevant information about symptoms, tests or medications. Often such inquiries leave doctors confused, wanting to help, but unable to do so. First of all, fever is not a disease, but a manifestation of a disease. There are many, many diseases that cause fever, the most common being infections (including various bacterial infections, viral infections, mycoplasma infections, etc.), followed by connective tissue diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis, etc.), and malignant neoplasms (e.g., leukemia, myeloma, etc.) and so on. If the doctor wants to diagnose the cause of fever, he or she usually needs to take a detailed medical history (including epidemiological information such as the region of incidence, season, age, occupation, living habits, history of travel and close contact with people with the same disease, history of surgery, history of blood transfusion and blood products, history of trauma, history of contact with cows and sheep, etc., which is of great significance in diagnosis, sometimes a little bit of discovery can provide important diagnostic clues) and needs to do a careful and systematic Physical examination, in the preliminary have a general judgment and then carry out the corresponding auxiliary examination, for further clarification of the cause of the disease to find evidence. Secondly, fever is both harmful and beneficial to the human body. Fever increases the body’s immune function, which is conducive to the removal of pathogens and promote the healing of the disease. Therefore, if the body temperature is not too high (less than 38.5 degrees), there is no obvious discomfort such as severe headache, generalized pain, you can delay taking antipyretics. After the use of antipyretics, the temperature can quickly normalize, but if the cause of the disease is not removed, the temperature will rise after the effect of the medicine. Finally, for infectious diseases, your doctor will give antimicrobial drugs. Antimicrobial drugs are not antipyretics, and it is not possible for the temperature to normalize immediately after the infusion of the drug. This is because antibacterials require a process, and the temperature can only be normalized if the cause of the disease is removed, a process that may take 2-3 days.