Drug fever.

Most medications can cause fever, with or without concomitant clinical manifestations. The fever may arise from the drug's pharmacologic action, its effects on thermoregulation, a local complication following parenteral administration, or an idiosyncratic response. The most common mechanism is probably an immunologic reaction mediated by drug-induced antibodies. Drug fever may have any pattern; it typically occurs after seven to ten days of treatment and usually resolves within 48 hours of discontinuing the administration. Failure to diagnose drug fever may lead to inappropriate and potentially harmful diagnostic and therapeutic interventions. In suspected cases, it is necessary to discontinue administration of all potentially causative medicines, together or sequentially. Rechallenge with the offending agent will usually cause recurrence of fever within a few hours, confirming the diagnosis.