A low-grade fever that doesn’t go away for a day, as long as the temperature is above the normal range is definitely a problem, but it just hasn’t been detected. Not all of the fever can be routine examination can be found out the cause of the disease, this situation consider to the hospital routine blood test and immune function. For example, cellular immunity, humoral immunity, trace elements. At the same time, we can see if there is any manifestation of tuberculosis, and if there is recurrent low-grade fever, we should consider whether there is any viral infection. Antiviral drugs, such as pyridostigmine and inflammatory sulfonylurea, should be considered in the treatment. In addition, anti-inflammatory drugs, such as azithromycin and penicillin, can be applied. At the same time need to do further related examination, in addition to see whether there are other symptoms, such as cough, cough sputum, sore throat or nausea, vomiting, diarrhea, or urinary symptoms. If there are symptoms, according to the symptoms of the symptomatic treatment. Generally, if the fever is low for more than 3-5 days, it is necessary to investigate the immune system and blood diseases.