DRUG FEVER

Drug fever is an uncommon but important cause of prolonged fever, defined as:

• Unexplained pyrexia during the course of specific drug therapy, and

• Normalization of temperature within one week of discontinuation of offending drug.

Clinical indicators: Drug fever is a diagnosis of exclu­sion, though following characteristics are strongly suggestive:

• Onset of fever within 24-48 hours of starting the offending drug,

• Low-grade persistent fever, rarely exceeding 39°C,

• Frequently, but not essentially, associated features, e.g. rash or eosinophilia,

[*] Disappearance of fever within 7 days of stopping the suspected drug,

• Reappearance of fever after re-instituting same drug. Mechanisms: Although frequently idiopathic, possible mechanisms in drug fever include:

• Presence of exogenous pyrogens in the preparation, e.g. IV amphotericin.

• Release of endogenous pyrogens due to specific drug action, e.g. antibiotics, cytotoxic agents.

• Inherent pharmacological action like reduced sweating, e.g. atropine or antihistaminics.

• Allergic response, e.g. sulpha-drugs or penicillin.

• Idiosyncratic reaction ? genetic predisposition for qualitative intolerance other than immunological mechanisms, e.g. quinine or sulpha drugs.

Management: No treatment is indicated except dis­continuation of the suspected drug, though symptomatic therapy may be used if the offending drug cannot be discontinued for medical reasons.

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