Fever without headache may be caused by infection, heat stroke, poisoning, autonomic dysfunction and other factors. 1. Infection: Bacteria, viruses, other pathogenic microorganisms, pathogen infection invades the organism, the body produces an immune response, mainly manifested as simple fever, and will not cause headache. 2. Heatstroke: hot weather in summer, prolonged exposure to high temperatures may cause aura heatstroke, mild heatstroke or severe heatstroke, which may cause simple fever. In addition to this, poisoning, autonomic dysfunction, severe anemia, hematologic tumors, tuberculosis, rheumatoid, rheumatic fever, rheumatoid arthritis, may also cause simple fever. It is recommended to pay close attention to the change of temperature in the axilla, and if necessary, go to the general internal medicine department of the hospital to find the cause of fever.