A child’s lack of energy after a fever is usually related to the body’s energy consumption and dehydration, the cause of the disease has not been removed and other pathological reasons. 1. high energy consumption: the child needs to consume a lot of energy during the fever process, which may make the child feel very fatigued and prone to have no energy after the fever goes away. 2. Dehydration: If the child has a severe fever and sweats a lot, and eats and drinks less water, the child may be dehydrated, which may also cause the child to have no energy after the fever goes away. 3. The cause of the disease has not been removed: If the bacteria and viruses that caused the fever are not completely removed, but the fever is no longer there, it can also lead to the child to have a fever and no energy. There may also be other reasons why your child has no energy after a fever, so we recommend that you go to the hospital in time, complete the examination to determine the cause of the illness, and then give targeted treatment or treatment under the guidance of the doctor.