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Dermatology

Erythema nodosum

Erythema nodosum is a tender septal panniculitis and reaction pattern, usually presenting with bilateral shin nodules that fade like bruises; the key task is identifying an infectious, inflammatory, drug-related, pregnancy-related or other trigger.

In a nutshell

Erythema nodosum is a tender septal panniculitis causing crops of palpable nodules, usually on the shins, that fade like bruises without ulceration or scarring. It is a reaction pattern: look for streptococcal or other infection, sarcoidosis, inflammatory bowel disease, tuberculosis, medicines and pregnancy, while recognising that many cases are idiopathic. Treat the cause and provide supportive analgesia and rest.

Classic presentation

A young adult develops bilateral tender shin nodules with ankle pain and malaise after a recent sore throat; the lesions evolve through bruise-like colours and do not ulcerate.

Key points

  • Tender bilateral shin nodules that resolve like bruises without ulceration or scarring are the classic pattern.
  • Erythema nodosum is a septal panniculitis and a reaction pattern, not a single underlying disease.
  • Look for infection, sarcoidosis, inflammatory bowel disease, tuberculosis, medicines and pregnancy; many cases remain idiopathic.
  • Use targeted tests guided by history and examination; biopsy atypical, ulcerated or persistent lesions rather than every classic case.
  • Löfgren syndrome is sarcoidosis with erythema nodosum, bilateral hilar lymphadenopathy and ankle or other periarticular arthritis.
  • NSAIDs can help pain but need a BNF and comorbidity check, especially in inflammatory bowel disease.
  • Persistent, recurrent, severe or atypical disease needs dermatology or relevant specialty review.

First-line investigation

Clinical assessment with targeted blood, infection, chest or gastrointestinal investigations guided by symptoms and risk; biopsy when the morphology or course is atypical.

Management

Confirm the pattern and screen for danger

  • Assess systemic state, pain, ulceration, necrosis, respiratory and bowel symptoms, TB risk and joint function; escalate atypical or seriously unwell presentations.2,1,5

Search for a clinically plausible cause

  • Use targeted tests for recent infection, inflammation, sarcoidosis, TB or inflammatory bowel disease, and review new medicines and pregnancy; accept idiopathic disease when the assessment is reassuring.2,1,5

Relieve pain while the eruption settles

  • Recommend rest, elevation, cool compresses and avoidance of prolonged standing or high-impact activity; use supportive bandaging and analgesia tailored to comorbidity.2,3,4

Treat the underlying disease

  • Treat a confirmed infection or inflammatory condition through its relevant pathway and review culprit medicines with the prescriber; do not suppress inflammation systemically before important infection has been assessed.2,5,4

Biopsy or refer when the pattern is not typical

  • Seek dermatology or relevant specialty input for atypical, ulcerated, persistent, recurrent, severe or unexplained lesions, or when systemic symptoms point to TB, sarcoidosis or inflammatory bowel disease.2,1

Safety-net the natural history

  • Review progression and investigation results, and ask the patient to return for worsening systemic symptoms, new respiratory or bowel features, ulceration, severe pain, recurrence or failure to settle by around 8 weeks.2,3

Exam traps

  • The lesions should not ulcerate or scar; ulceration suggests another panniculitis, vasculitis or infection.
  • Bilateral erythema nodosum is not cellulitis and should not trigger reflex antibiotics.
  • Do not order a blanket panel without a history: investigate TB, sarcoidosis, infection, inflammatory bowel disease and drugs according to clinical clues.
  • A positive streptococcal test may indicate a trigger but does not replace assessment for other causes.
  • Avoid NSAIDs or seek specialist advice in inflammatory bowel disease.
  • Do not start systemic corticosteroids before considering important infection, especially tuberculosis.

Illustrations

Erythema nodosum on the lower legClinical photograph of a tender erythematous-to-violaceous raised subcutaneous nodule on the distal lower leg, typical of erythema nodosum.ErikH at Dutch Wikipedia, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. Primary Care Dermatology Society: Erythema nodosum (UK professional clinical guidance on differential diagnosis, focused investigations and management; last updated 28 May 2022 and accessed 4 August 2026.)Updated 28 May 2022
  2. NHS: Erythema nodosum (Current NHS information on presentation, common causes, self-care, when to seek assessment, biopsy and treatment; accessed 4 August 2026.)
  3. British Association of Dermatologists: Erythema nodosum patient information leaflet (BAD consensus information on typical lesions, likely causes, natural history and supportive care; updated April 2021 and accessed 4 August 2026.)Updated 1 Apr 2021
  4. British National Formulary (BNF) (BNF online prescribing information for analgesics, NSAIDs, corticosteroids and interactions; current prescribing details must be checked at the point of care; accessed 4 August 2026.)
  5. NICE NG33: Tuberculosis (NICE UK tuberculosis guideline for investigation and escalation when TB is suspected; accessed 4 August 2026.)Updated 16 Feb 2024

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.