Coma followed by fever is most commonly associated with severe brain lesions. There are many causes of coma, including brain lesions, severe infections, serious systemic disorders, hepatic coma, poisoning, and hypoglycemia, which can lead to coma due to disruption of the brainstem reticular up-activation system. Severe brain lesions can disrupt the brainstem upstream activation system and can also damage the hypothalamic thermoregulatory center and cause central hyperthermia, which is a rapid rise in body temperature without obvious signs of infection and can rapidly rise above 40°C. The use of antibacterial drugs is ineffective and can only rely on physical cooling to lower the body temperature. Coma with complications such as pulmonary infection or urinary tract infection can also occur in severe lesions, but usually laboratory tests and ancillary tests will indicate that the body has an infection.