37.9℃ is considered a fever, which is low. The normal body temperature of the human body is between 36℃-37.3℃, over 37.3℃ is considered fever. Many diseases can cause low fever. A temperature of 37.9℃ may be caused by a cold or inflammation in the body, and is mostly seen in some infectious diseases, such as bacterial infection, fungal infection, viral infection, Mycobacterium tuberculosis infection, mycoplasma or chlamydia infection. Infectious diseases require anti-infectious treatment to bring down the body temperature. Blood tests can be done to identify the infectious agent and then targeted treatment can be given. There are also non-infectious diseases, such as rheumatic immune diseases, connective tissue diseases, and hyperthyroidism, which can cause low-grade fever. Body temperature 37.9 ℃ need to find the specific cause of the disease, according to the cause of the systematic and standardized treatment. Body temperature 37.9 ℃ belongs to low fever, did not exceed 38.5 ℃, do not need to use antipyretic drugs for treatment, can be through the physical cooling method or drink more warm water to promote cooling, and pay attention to warmth, observation of body temperature changes. If the fever does not go down or the temperature continues to rise, you need to go to the hospital in time to avoid delaying your condition.