The precursors of fever are various, with different causes and different fevers, which may be asymptomatic or may show some systemic symptoms. 1. For the fever caused by some conditions, for example, the fever caused by tuberculosis, the patient usually has no obvious symptoms before the fever, mostly manifested as low fever in the afternoon. 2. Fever may also be caused by other reasons, such as tumor fever, fever caused by connective tissue diseases, etc., often without specific precursors. 3. However, for fever caused by infectious diseases, such as acute upper respiratory tract infections, the fever is usually preceded by symptoms such as chills, dizziness, headache, and fatigue. When fever symptoms appear, do not blindly treatment, it is best to go to the hospital in time, cooperate with the doctor examination and treatment.