What is the role of lab testing in the diagnosis of drug eruptions?

Updated: Oct 14, 2020
  • Author: Jonathan E Blume, MD; Chief Editor: Dirk M Elston, MD  more...
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With mild asymptomatic eruptions, the history and physical examination are often sufficient for diagnosis; with severe or persistent eruptions, further diagnostic testing may be required, as follows:

  • Biopsy

  • Complete blood count (CBC) with differential

  • Serum chemistry studies (especially for electrolyte balance and indices of renal or hepatic function in patients with severe reactions)

  • Antibody or immunoserology tests

  • Direct cultures to investigate a primary infectious etiology or secondary infection

  • Urinalysis, stool guaiac tests, and chest radiography for vasculitis

  • Skin prick or patch testing to confirm the causative agent

See Workup for more detail.

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