Last reviewed: February 2018
Last updated: May  2017



History and exam

Key diagnostic factors

  • target lesions of the extremities
  • recurrent disease
  • mucosal erosions

Other diagnostic factors

  • targetoid lesions
  • rapid onset of lesions
  • self-limited course
  • clustered vesicles on an erythematous base
  • rhonchi, rales, and/or wheezes
  • red tympanic membranes
  • hepatomegaly

Risk factors

  • prior occurrence
  • herpes simplex virus (HSV) infection
  • cytomegalovirus infection (CMV)
  • Epstein-Barr virus (EBV) infection
  • mycoplasma pneumonia
  • hepatitis B virus infection
  • histoplasmosis
  • HIV infection
  • Lymphoma
  • orf virus infection
  • medications
  • paraphenylenediamine in henna tattoos
  • hepatitis B vaccine
  • syphilis

Diagnostic investigations

1st investigations to order

  • CBC
  • serum electrolytes
  • herpes simplex virus (HSV) serology
  • rapid PCR
  • cold-hemagglutination serology
  • M pneumoniae titers
  • CXR
Full details

Investigations to consider

  • hematoxylin and eosin biopsy
  • immunofluorescence biopsy
  • hepatitis B virus (HBV) serology
  • LFTs
Full details

Emerging tests

  • antidesmoplakin antibodies
Full details

Treatment algorithm


Authors VIEW ALL

Assistant Professor

Department of Surgery

Rush University Medical Center




AK-V has received compensation for reviewing manuscripts for Rubriq from Research Square on a variety of topics, including erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis. She is also a manuscript reviewer for several journals, without renumeration.

Dr Areta Kowal-Vern would like to gratefully acknowledge Dr Jonathan Silverberg and Dr Nanette Silverberg, the previous contributors to this monograph. JS and NS declare that they have no competing interests.

Peer reviewers VIEW ALL

Staff Physician

Cleveland Clinic




CR declares that she has no competing interests.

Clinical Assistant Professor

University of Iowa College of Medicine

Iowa City



BS declares that he has no competing interests.

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