Fever is generally divided into infectious fever and non-infectious fever, and infectious fever can be caused by the invasion of pathogens such as bacteria, viruses, fungi, mycoplasma, rickettsia and other pathogens into the organism to cause infection. The most common pathogens of infectious fever are bacteria, such as purulent bacterial infections (including sepsis, typhoid fever, infective endocarditis, etc.), often caused by Gram-negative or positive bacteria, and blood cultures are usually needed to clarify the cause. There are also respiratory diseases, such as pneumonia, lung abscess and abscess chest, which require sputum culture to identify the pathogen. Next is Mycobacterium tuberculosis (such as pulmonary tuberculosis and intestinal tuberculosis). The clinical manifestations of tuberculosis are usually low fever in the afternoon, night sweats, malaise, loss of appetite and emaciation, which can be diagnosed with the help of X-ray or tuberculin test. Viral infectious fever with normal or mildly decreased white blood cell count and relatively or absolutely increased lymphocyte count, classified up to 60% or more. positive C-reactive protein assay (CRP) indicates bacterial infection or rheumatic fever, while viral infection is mostly negative. Infectious fever should be treated with effective medications selected according to the source of infection. For infectious fever, fever itself is one of the manifestations of the body’s immune system to clear the source of infection. Unless the fever is high and the patient is in serious discomfort and strongly requested, there is usually no need to use antipyretic drugs urgently, and physical cooling can be taken first to relieve the fever symptoms. For specific medication and dosage, you should go to the hospital for a face-to-face consultation and use the medication under the guidance of a doctor.