Fever is only a symptomatic manifestation, and if there is a state of fever that does not go away, in most cases the cause of the illness has not been relieved. In the more common case of an upper respiratory tract infection with a fever that does not go away, there is also the possibility of an uncontrolled viral or bacterial infection. Others may be infectious diseases, such as tuberculosis, paratyphoid fever, brucellosis, deep septic bacterial infections; then there are long-term unspecified connective tissue diseases, such as lupus erythematosus, atypical rheumatic fever, polyarteritis nodosa, and so on, and then there are some long-term unspecified hematological disorders, such as lymphomas, acute non-lymphocytic leukemia, multiple myeloma, and so on; for the prolonged low-fever cases We should pay attention to some inflammation, for example, sinusitis, otitis media, some purulent periodontitis, and then for the body to be alert to the possibility of hyperthyroidism, as well as some malignant tumors, and then some physiological low fever, for example, pregnant women with metabolism increase and low fever, after delivery the temperature will return to normal, and then some of the summer summer heat and low fever and the regulation of the ability of the weaker, some anxiety, easy to agitation and nervousness of women, body temperature is also fluctuating, and the body temperature is also low. Nervous women, body temperature fluctuation is not more than 0.5 degrees, fever and emotions. With a state of fever that does not go away, it must be diagnosed and analyzed in conjunction with the accompanying symptoms. In most cases it is necessary to consult a doctor in time, who performs an on-site examination and identification.