Cellulitis 🦵
UK guide to recognising and managing cellulitis and erysipelas in adults: NICE NG141 antibiotic pathways, marking progress, red flags, MRSA cover, 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 antimicrobial 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.
- Exclude non-infectious redness where relevant (for example insect bite reaction, chronic venous insufficiency).
- Redness may be less visible on darker skin tones. Mark borders to track spread.
🚨 Red Flags — Escalate Urgently
- Sepsis, necrotising fasciitis, orbital cellulitis, osteomyelitis, or septic arthritis: emergency assessment / hospital referral.
- Rapidly spreading or deteriorating infection despite oral antibiotics: needs IV therapy and senior review.
- Infection near the eyes or nose (including periorbital cellulitis): lower threshold for specialist advice and co-amoxiclav pathway.
- Uncommon pathogens: penetrating injury, water-borne exposure, or infection acquired outside the UK.
- 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, NEWS2, and sepsis screen if systemically unwell (see Sepsis).
- 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, venous insufficiency, lymphoedema, oedema (including calcium-channel blocker related), eczema, immunosuppression.
- Swab only if the skin is broken and there is penetrating injury, water-borne exposure, or infection acquired outside the UK. Consider swab on reassessment if not already done.
- Take account of previous swab results and known MRSA status when choosing antibiotics.
- 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. A longer course (up to 14 days total) may be needed on clinical assessment. Full skin normalisation takes longer.
- Give oral antibiotics first line if the person can take oral medicines and severity does not require IV therapy.
- If IV antibiotics are given, review by 48 hours and switch to oral when possible.
- 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 (NICE NG141)
- First-choice for uncomplicated cellulitis or erysipelas in adults aged 18 and over.
- Confirm local Trust AMS / resistance patterns. Oral first line if suitable.
- See BNF for hepatic/renal impairment, pregnancy, and breastfeeding.
💊 Antibiotics — Penicillin allergy (NICE NG141)
- Alternative first-choice options when penicillin allergic or flucloxacillin unsuitable.
- Erythromycin is preferred if a macrolide is needed in pregnancy (see MHRA macrolide advice).
- Avoid doxycycline in pregnancy.
💊 Antibiotics — Near eyes or nose (NICE NG141)
- Infection in the triangle from the bridge of the nose to the corners of the mouth, or immediately around the eyes (including periorbital cellulitis), carries intracranial complication risk.
- Consider seeking specialist advice.
- Course length 7 days for these regimens.
💊 Antibiotics — Severe infection alternatives (NICE NG141)
- For severe infection when first-line options are unsuitable. Confirm Trust AMS and microbiology advice.
- Ceftriaxone is listed for ambulatory care only; other agents may be appropriate on specialist advice.
🦠 MRSA & Microbiology
- If MRSA is suspected or confirmed, add an agent such as vancomycin, teicoplanin, or linezolid (specialist use) in combination with an antibiotic from the tables above. Confirm with microbiology and Trust AMS.
- Other agents may be appropriate based on susceptibility results.
- Review antibiotic choice when swab results return. Narrow spectrum if symptoms are not improving.
- Animal or human bites: use local bite pathway, not standard cellulitis monotherapy alone.
🔁 Recurrent Cellulitis
- Do not routinely offer antibiotic prophylaxis. Give advice on seeking help if symptoms recur.
- For adults with at least two separate treated episodes in the previous 12 months (hospital or specialist advice), specialists may consider a prophylaxis trial after shared decision-making.
- Address predisposing factors: tinea pedis, leg oedema, venous insufficiency, lymphoedema, skin barrier care, eczema, diabetes.
- If prophylaxis is used, review at least every 6 months. Stop or change if ineffective or cellulitis recurs.
- Specialist prophylaxis choices (when used): phenoxymethylpenicillin 250 mg BD, or erythromycin 250 mg BD if penicillin allergic. Prefer a different agent from recent treatment courses when possible.
🩹 Supportive Care & Patient Advice
- Paracetamol ± ibuprofen if appropriate for pain and fever. Maintain hydration.
- Advise on possible antibiotic adverse effects.
- 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. Full resolution at 5–7 days is not expected.
- Switch IV to oral when improving. See antibiotic IV-to-PO for inpatients.
Related NICE guidance
NICENICE NG141 — Cellulitis and erysipelas: antimicrobial prescribing
Full guidance on nice.org.uk. BetterCall is not endorsed by NICE.
External resources
Note Template
Ready-to-use clinical note structure
🕒 08 / 10 / 2026 — 16:03 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: _______
Educational reference only. Medical disclaimer