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Cellulitis and Erysipelas

NICE guideline [NG141] Cellulitis and erysipelas: antimicrobial prescribing. Published: Sep 2019. NICE CKS Cellulitis - acute. Last revised: Nov 2024.

Background Information

Cellulitis: deep skin infection, involving the dermis and subcutaneous tissue

Erysipelas: superficial skin infection, involving only the upper dermis

Most common causative agents:
  • Cellulitis: Staphylococcus aureus, Group A strep (Streptococcus pyogenes)
  • Erysipelas: Group A strep (Streptococcus pyogenes)

Guidelines

Cellulitis and erysipelas is a clinical diagnosis.

Only consider taking a swab for microbiology to guideline treatment if:
  • Skin is broken, and
  • Penetrating injury / exposure to water-borne organisms / infection acquired outside the UK

Eron classification system:
 
Eron Class Description
I
  • No systemic toxicity, and
  • No uncontrolled comorbidities
II
  • Systemically unwell, or
  • With comorbidity (e.g. PADPeripheral arterial disease, chronic venous insufficiency, morbid obesity)
III
  • Significant systemic upset (e.g. acute confusion, tachycardia, tachypnoea, hypotension), or
  • Vascular compromise, or
  • Unstable comorbidities
IV
  • Sepsis, or
  • Life-threatening infection (e.g. necrotising fasciitis)

Essentially, Eron class II - IV requires hospital referral (see above), and
  • Severely immunocompromised patients
  • Other serious conditions
    • Septic arthritis
    • Osteomyelitis
    • Orbital cellulitis
 

Base urgency on clinical judgement, for instance it is sensible to refer immediately to emergency department in Eron class IV.

Consider drawing around the extent of the infection (edge of the redness) with a surgical marker pen to monitor progress.

Route of administration:
  • 1st line: oral antibiotics
  • If cannot tolerate oral medications / severely unwell → IV antibiotics
 

Standard choice of antibiotics in adults (>18 y/o):

  • 1st line: flucloxacillin (5-7 days)

  • 2nd line: clarithromycin / erythromycin / doxycycline

See below for the choice of antibiotics in various scenarios and patient populations:
 

  • 1st line: co-amoxiclav
  • 2nd line: clarithromycin + metronidazole

Any of the following
  • Co-amoxiclav
  • Cefuroxime
  • Clindamycin
  • Ceftriaxone (only IV route available)

Combination therapy: combine 1 from this list here + 1 from above:
  • Vancomycin
  • Teicoplanin
  • Linezolid

Essentially same as above, but doxycycline should not be used:
  • 1st choice antibiotic still flucloxacillin
  • Same antibiotics in other situations (apart from no doxycycline)

  • 1st line: flucloxacillin (penicillin is safe during pregnancy)
  • 2nd line: erythromycin (preferred over clarithromycin and doxycycline)

References

Author: Adams Lau
Reviewer: 
Last edited: 14/07/25