Drug fever is the febrile response to a drug without cutaneous manifestations. Although the exact incidence of drug fever remains unknown, it has been estimated to occur in approximately 10% of inpatients. The recognition of drug fever is of great clinical importance because, if drug fever is not recognized diagnostically, patients may be subjected to prolonged hospitalization and unnecessary testing or medications. Early diagnosis and treatment of drug fevers are essential in maintaining cost-effective, high-quality medical care.