A child with a temperature of 40 degrees is considered to have a high fever, it is more dangerous and prone to febrile convulsions, leading to lack of oxygen to the brain. If it lasts for a long time, it may lead to irreversible damage to brain cells, so it must be given timely antipyretic treatment. Children’s nervous system development is not perfect, more sensitive to fever and high fever, 40 degrees is already a high fever state, if not controlled, there will be high fever convulsions, may cause brain damage, serious cases even shock, epilepsy, so the first thing to do to reduce heat. You can do physical cooling, such as cold water baths, because the evaporation of liquid will take away heat and help improve the symptoms of fever; you can also use ice pillows or wear ice caps, which can reduce the temperature of the brain and ensure that the central nervous system is not damaged. Fever-reducing medications, such as ibuprofen suspension, should also be taken, and fever-reducing suppositories can also be used. At the same time, parents need to take their children to the hospital in time to check the blood routine, C-reactive protein, chest X-ray, etc., to clarify the cause of high fever and then give corresponding treatment. During the period of fever reduction, parents should give their children more water to prevent dehydration and metabolic disorders, and eat a light diet with more vegetables and fruits to supplement vitamins.