Malaise with low afternoon fever may be due to infection, rheumatic immune system disease, hyperthyroidism. The treatment is generally attention to rest, medication and so on. 1. Infection: Bacterial and viral infections, the body’s immune resistance will cause low fever, fatigue symptoms, may appear in the afternoon low fever. If it is common bacterial infection, cefaclor tablets, cefprozil tablets and other anti-inflammatory treatment can be given according to the doctor’s instructions; if it is viral infection, anti-viral drugs such as buspirone oral solution, ribavirin granules and so on can be given according to the doctor’s instructions. 2. Rheumatic immune system diseases: for example, ankylosing spondylitis, due to autoimmune disorders and inflammatory stimuli, may also cause fatigue afternoon low fever phenomenon. Anti-inflammatory treatments such as meloxicam tablets and injectable etanercept can be given under medical advice. 3. Hyperthyroidism: due to hyperthyroidism, resulting in increased secretion of thyroid hormones, can lead to hormonal disorders in the body, affecting the central temperature control system, may also appear weakness afternoon low fever phenomenon. Thyroid hormone synthesis can be inhibited by administering propylthiouracil tablets and formamide imidazole tablets under medical advice. It is recommended to visit the hospital when the above symptoms persist for early diagnosis and treatment. The use of medication should be under the guidance of a doctor and should not be used blindly.