Cellulitis 🦵
Guide to recognising and managing cellulitis and erysipelas in adults: HSE antibiotic pathways, marking progress, red flags, MRSA risk, and when to escalate to IV therapy or secondary care.
📖 Definition & Presentation
- Acute bacterial infection of the dermis and subcutaneous tissues — diagnosis is clinical.
- Typical features: spreading erythema, warmth, swelling, tenderness, and pain; systemic upset (fever, malaise) is common.
- Erysipelas: more superficial infection with brighter erythema, raised skin, and sharper demarcation — managed on the same HSE cellulitis pathway.
- Leg is the commonest site; look for a portal of entry ( wound, ulcer, tinea, interdigital fissure ).
- Bilateral lower-leg “cellulitis” is uncommon — consider venous eczema, lipodermatosclerosis, contact dermatitis, or DVT.
- Usual pathogens: Streptococcus pyogenes and Staphylococcus aureus.
- Redness may be less visible on darker skin tones — mark borders to track spread (see HSE patient information for typical appearance).
🚨 Red Flags — Escalate Urgently
- Sepsis, necrotising fasciitis, orbital/periorbital cellulitis, osteomyelitis, or septic arthritis — emergency assessment.
- Rapidly spreading or deteriorating infection despite oral antibiotics — needs IV therapy and senior review.
- Infection near the eyes or nose — lower threshold for secondary care advice and co-amoxiclav (see HSE table).
- Diabetic foot infection with vascular compromise — same-day urgent secondary care (osteomyelitis risk).
- Immunocompromise, lymphangitis, crepitus, severe pain out of proportion, or blistering/necrosis.
- Unable to take oral antibiotics — consider IV therapy per local protocol / OPAT where available.
🔍 Assessment
- Vitals, NEWS/MEWS, and sepsis screen if systemically unwell.
- Map the area: draw around erythema with a single-use surgical marker (redness harder to see on darker skin).
- Examine for portal of entry; in leg cellulitis inspect toe webs and treat tinea/interdigital infection if present.
- Assess for lymphangitis, lymphadenopathy, bullae, abscess, or joint involvement.
- Comorbidities: diabetes (consider HbA1c if not known), venous insufficiency, lymphoedema, obesity, immunosuppression.
- Swab wound/discharge only if open wound, discharge, atypical infection, or MRSA/PVL suspected — diagnosis is clinical.
- Consider DVT, gout, allergic/contact dermatitis, superficial thrombophlebitis if atypical.
📏 Monitoring & Review
- Some increase in redness in the first 24–48 h of antibiotics can occur — mark borders to track true spread.
- Review if not improving within 2–3 days, or if worsening at any time.
- Course usually 5–7 days; may extend up to 14 days total based on clinical response (full skin normalisation takes longer).
- Elevate affected limb; avoid compression garments during acute cellulitis.
- Document marker pen used, antibiotic start time, and plan for GP follow-up on discharge.
💊 Antibiotics — Standard adult (HSE)
- First-line for uncomplicated limb cellulitis in adults (including erysipelas).
- If afebrile and otherwise healthy, flucloxacillin monotherapy is appropriate per HSE.
- Take flucloxacillin on an empty stomach (1 h before or 2 h after food) for absorption.
- In diabetes or venous insufficiency, consider up to 1 g QDS (off-label) for impaired circulation.
💊 Antibiotics — Penicillin allergy (HSE)
- Choose alternative based on severity of penicillin allergy.
- Do not use cephalosporins in severe penicillin allergy.
- Clarithromycin: use with caution in pregnancy (2nd/3rd trimester only). Clindamycin option in pregnancy with severe penicillin allergy — C. difficile risk.
💊 Antibiotics — Near eyes or nose (HSE)
- Periorbital/facial cellulitis — consider seeking secondary care advice.
- Co-amoxiclav is first-line when not penicillin allergic.
- Add anaerobic cover (metronidazole) with cefalexin or clarithromycin in penicillin allergy regimens below.
🦠 MRSA & Microbiology
- Seek microbiology advice if MRSA suspected or isolated.
- MRSA risk: prior MRSA, frequent healthcare contact, recent admission to high-prevalence facility.
- Consider swab if PVL-S.aureus suspected (recurrent boils/carbuncles, contact sports, poor hygiene) — include nasal carriage swab.
- See HPSC Group A Streptococcus guidance if clinically indicated.
- Animal or human bites — use HSE bite guideline, not standard cellulitis monotherapy alone.
🔁 Recurrent Cellulitis
- Recurrent = more than two episodes at the same site within one year.
- Address predisposing factors: tinea pedis, leg oedema, venous insufficiency, lymphoedema, skin barrier care.
- Do not routinely offer antibiotic prophylaxis — out-rule secondary causes; refer if ongoing concern.
- Refer lymphoedema and recurrent cellulitis with venous insufficiency to secondary care.
- If prophylaxis is used, review every 6 months and stop if ineffective or no episodes in 12 months.
🩹 Supportive Care & Patient Advice
- Paracetamol ± ibuprofen if appropriate for pain and fever; maintain hydration.
- Emollients to reduce skin cracking; manage interdigital tinea and leg ulcers.
- Seek urgent review if rapid spread, increasing systemic symptoms, or intolerance to antibiotics.
- Skin colour may take time to normalise after antibiotics — advise expected recovery course.
- Switch IV to oral when improving — see antibiotic IV-to-PO topic for inpatients.
🔗 Related Topics
Based on
Note Template
Ready-to-use clinical note structure
🕒 10 / 07 / 2026 — 00:39 ATRP re: cellulitis / erysipelas Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: [diabetes, venous insufficiency, lymphoedema, immunosuppression] 🧾 Hx: • Onset: [date] — site [leg / face / other] • Spread, pain, fever, systemic symptoms • Portal of entry: [wound / ulcer / tinea / none found] • Prior cellulitis / MRSA / recent healthcare contact • Allergies: penicillin [Y/N — severity if known] 🩺 Exam: • Vitals: HR __ BP __ Temp __ • Erythema marked with pen: [yes/no] — site and approximate size • Portal of entry / toe webs / leg ulcer: [findings] • Lymphangitis / abscess / joint involvement: [yes/no] • Bilateral: [yes/no — if yes reconsider diagnosis] 🔬 Investigations: • Bloods if systemically unwell: FBC, CRP, U&E, lactate • Wound swab: [sent / not indicated] • DVT workup: [if atypical] 📋 Impression: Cellulitis / erysipelas — [uncomplicated / periorbital / severe / recurrent] 📌 Plan: • Antibiotics per HSE cellulitis v2.1: [flucloxacillin / alternative / co-amoxiclav] • Analgesia, limb elevation, mark borders, review 48–72 h • Referrals: [microbiology / dermatology / vascular / ophthalmology — or none] • Safety-netting: worsening spread, systemic symptoms, eye involvement 👤 [Your Name], [Role] IMC: _______