The sequelae of fever include: 1. Because high fever easily causes dehydration, while taking antipyretic drugs with a lot of sweating, the body loses too much water, the blood sodium concentration rises, the blood is hypertonic, the child will have dry mouth, thirst, irritability, the fever does not go down, but will be higher, may appear hyponatremia, mostly seen in infants and children who usually have malnutrition. 2. Some children will have cramps, or even febrile convulsions, cramps The fever is not long and the child’s health is not affected as long as the convulsions are handled properly. 3, the general fever does not affect the body tissues and organs, and can accelerate the generation of resistance, but when the body temperature exceeds 41 ℃, the decomposition of proteins in the body will occur, causing brain edema and disease, the child can die or leave sequelae of encephalopathy. Therefore, children with high fever above 40℃ must be treated urgently.4. Small infants may have a rapid heartbeat due to high fever, which may also cause heart failure, etc.