Children’s fever and headache with generalized weakness may be related to conditions such as influenza, upper respiratory tract infection and myocarditis. 1. Influenza: Influenza is usually caused by influenza viral infection, which usually results in fever, generalized weakness, headache, generalized muscle pain, nasal congestion, runny nose and other symptoms. 2. Upper respiratory tract infection: Upper respiratory tract infection caused by bacteria can also cause children to have fever, headache, general weakness and other symptoms. 3. Myocarditis: In addition to the fever, headache and generalized weakness that may occur in children, myocarditis is usually accompanied by chest tightness, discomfort in the precordial area and increased heart rate. Children’s fever, headache and generalized weakness may also have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.