Thyroiditis is generally classified into three types. The first type is chronic thyroiditis, among which chronic lymphocytic thyroiditis is common, also known as Hashimoto's thyroiditis. It is an autoimmune thyroid disease and generally does not cause fever. Another type is acute thyroiditis, where the local thyroid area, due to bacterial or viral infection, leads to a suppurative disease, which may be accompanied by fever. The third type is called subacute thyroiditis, which generally occurs after an upper respiratory tract infection and can manifest as thyroid pain, sometimes accompanied by symptoms of fever.