In most cases, fever will not burn the child silly, but when the body temperature is too high, some children may have febrile convulsions, which can cause brain damage due to lack of oxygen if the convulsions last too long. Without febrile convulsions, a fever will not burn your child silly, but a fever can bring many harmful effects to the body. A sustained high fever can cause an increase in metabolism, resulting in increased heart rate and respiration. The cause of the fever needs to be identified as soon as possible to address the root cause of the fever, which may be more serious than the damage caused by the fever.