The causes of high fever for 5 days in children include the following: firstly, it is caused by various infections. When children are infected with viruses, bacteria or Mycoplasma pneumoniae, if the degree of infection is very serious, it will cause high fever for 5-6 days, etc. In particular, children with influenza A virus or influenza B virus will have high fever for 5 days. In particular, if a child has influenza A or influenza B, he or she may have a high fever lasting for 5 days, accompanied by headache, weakness, and sore throat, which requires prompt antiviral treatment such as Paramivir. Secondly, the symptoms are caused by Kawasaki disease. Children with Kawasaki disease may have a high fever that lasts for 5 days, accompanied by enlarged lymph nodes and dilated coronary arteries, which may lead to coronary aneurysms.