Adults have low fever for several days in a row, first of all, we should identify the cause of low fever and treat for the cause. The human armpit temperature between 37.3～38℃ belongs to low fever, usually caused by infection or other diseases, need to check the blood routine, clear the cause of the disease to choose the appropriate drugs for treatment. 1. If it is caused by bacterial infection, it is necessary to carry out bacterial culture to clarify which kind of bacterial infection is Gram-positive cocci, Gram-negative bacilli, Mycobacterium tuberculosis, etc., and then choose the appropriate medication for the causative bacterium, such as tuberculosis mycobacterium infection to take isoniazid and rifampicin and other medications. 2. If it is caused by viral infection, the cause can be clarified through blood test, serum antibody test, etc. If it is adenovirus, hepatitis B virus, etc., it needs different degrees of antiviral treatment, such as taking oseltamivir to treat influenza virus infection. If it is rotavirus, it does not need antiviral treatment, but only symptomatic treatment. 3. In the case of tumors or anemia, etc., low-grade fever can occur due to low immunity and needs to be treated for the primary disease. The causes of prolonged low-grade fever are very complicated, so it is recommended to go to a regular hospital for examination to clarify the causes.