A child with a high fever of 40 degrees Celsius is already very high, but the spirit is good because it may be in the early stages of the disease, and the child’s excitability increases in the case of high fever, so the spirit is better. You must closely observe the changes in the condition. When the fever is 40℃, it means that the cause of the fever is more serious, often infectious, and more serious, so the child should be immediately and actively reduce the fever by taking oral antipyretics, such as ibuprofen or acetaminophen, as well as applying cooling patches, taking warm baths and other physical cooling methods to help reduce the fever. In addition to actively reducing the fever, you should also take your child to the pediatric emergency room as soon as possible to identify the cause and treat the cause. Only when the cause is removed and the infection is effectively controlled will the fever not recur, otherwise not only will the fever recur, but other clinical symptoms may appear afterwards, leading to poor mental health.