• Clinical science

Erythema nodosum


Erythema nodosum (EN) is an inflammation of subcutaneous fat caused by a delayed hypersensitivity reaction. Women in early adulthood are commonly affected. Most cases are idiopathic, but an association with a variety of diseases, including infections and autoimmune disorders (e.g., ulcerative colitis), is possible. The characteristic lesions are painful nodules on the lower legs (particularly shins). EN is a clinical diagnosis. The condition typically heals spontaneous within a few weeks and therefore generally requires no more treatment than supportive care (e.g., analgesia).


  • Sex: >
  • Peak incidence: 18–34 years


Epidemiological data refers to the US, unless otherwise specified.





Clinical features

  • Non-specific symptoms: : fever, arthralgia , malaise, hilar lymphadenopathy
  • Painful, subcutaneous nodules on both pretibial (anterior leg) surfaces (less common on other areas of skin)
    1. Firm, erythematous (1st week)
    2. Fluctuant (without suppuration) and bluish (2nd week)
    3. Progressively fades (i.e., yellow or brown hue)



  • Usually a clinical diagnosis
  • Imaging and laboratory tests determine the underlying condition
  • Skin biopsy if diagnosis is uncertain



  • Symptomatic treatment
    • Bed rest
    • Leg elevation
    • Heat or cool compresses
    • NSAIDS (e.g., ibuprofen)
    • Potassium iodide
  • Treat underlying disease
  • In severe or refractory cases: systemic steroids



  • Usually self-limiting (within 2–8 weeks), or resolves earlier with effective treatment of underlying disease
  • Recurrence following discontinued treatment is common


  • 1. Hebel JL, James WD. Erythema Nodosum . In: Erythema Nodosum . New York, NY: WebMD. http://emedicine.medscape.com/article/1081633-overview. Updated March 3, 2016. Accessed June 7, 2017.
  • 2. Agabegi SS, Agabegi ED. Step-Up To Medicine. Baltimore, MD, USA: Lippincott Williams & Wilkins; 2013.
  • 3. Kroshinsky D, Callen J, Ofori AO, Romain PL. Erythema Nodosum. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/erythema-nodosum. Last updated November 30, 2016. Accessed June 23, 2017.
  • 4. Agabegi SS, Agabegi ED. Step-Up To Medicine. Baltimore, MD, USA: Wolters Kluwer Health; 2015.
  • 5. Le T, Bhushan V, Chen V, King M. First Aid for the USMLE Step 2 CK. McGraw-Hill Education; 2015.
  • 6. Gupta M, Singh K, Lehl SS, Bhalla M. Recurrent erythema nodosum: a red flag sign of hidden systemic vasculitis. BMJ Case Rep. 2013. doi: 10.1136/bcr-2013-009507.
  • Herold G. Internal Medicine. Cologne, Germany: Herold G; 2014.
last updated 01/29/2019
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