Drug-Induced Hypersensitivity Syndrome Followed by Subacute Thyroiditis.

Drug-induced hypersensitivity syndrome (DIHS) is a severe multiorgan system adverse drug reaction with reactivation of human herpesviruses (HHVs) such as HHV-6, HHV-7, cytomegalovirus (CMV) and Epstein-Barr virus. Various complications, including autoimmune diseases, sometimes appear during the course of DIHS. We report a case of salazosulfapyridine-induced DIHS associated with HHV-6 reactivation. Two and a half months after the onset of DIHS, subacute thyroiditis occurred, possibly associated with CMV reactivation. Prednisolone (20 mg/day) was effective for subacute thyroiditis. Long-term follow-up is needed in patients with DIHS because of the possible onset of autoimmune diseases.