Infants with a fever of 39℃ generally do not affect intelligence, but a few infants have the possibility of febrile convulsions, which can produce irreversible damage to brain cells 15 minutes after the onset of febrile convulsions, so they need to be taken seriously. Infants with a body temperature of 39℃ are in a high fever state and should be actively cooled down. A high fever not only causes discomfort, but an overly high body temperature may also cause convulsions and result in brain damage. It is usually necessary to use antipyretic suppositories, or take special antipyretic drugs for infants to make them reduce fever quickly, and pay attention to the dosage. At the same time, physical cooling should be performed by giving the infant warm water and rubbing the body with warm towels to promote capillary dilation and increase heat dissipation. If the fever does not subside after physical therapy and medication, the infant needs to be treated in the pediatric emergency department of the hospital to prevent loss of consciousness, muscle twitching and other febrile convulsive reactions that can cause serious damage to brain cells.