Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Sepsis, thrombosis or cardiopulmonary toxicity
A hot rapidly swollen limb with systemic illness, sudden cyanotic arm swelling, fever during chemotherapy, acute dyspnoea, syncope or new heart failure may represent cellulitis, upper-extremity DVT, neutropenic sepsis, embolism or treatment-related cardiac or lung injury.
Action: Use ABCDE assessment, send cultures and blood tests, start time-critical antibiotics or anticoagulation when indicated, obtain urgent venous or cardiopulmonary imaging and involve acute oncology and the breast team; do not label an acute unilateral swollen arm as routine lymphoedema before excluding dangerous alternatives.
Synopsis
Recognise acute and late breast-treatment toxicity, diagnose arm or breast lymphoedema without missing thrombosis or recurrence and deliver early compression, movement, skin, infection, pain and survivorship management.
Breast-treatment lymphoedema can affect arm, hand, breast, chest wall or trunk and may arise months or years after axillary surgery or nodal radiotherapy.
Key early symptoms are heaviness, tightness, transient swelling, jewellery or clothing change and reduced flexibility; visible enlargement may appear only after a reversible phase.
Diagnosis is primarily clinical with standardised circumference, volume or bioimpedance assessment. Acute or atypical swelling requires venous thrombosis, infection and recurrence exclusion first.
Key red flags
Fever, rigors, spreading erythema, severe pain, hypotension or confusion in a lymphoedematous limb suggests cellulitis with possible sepsis.
Cellulitis
Rapid warmth, erythema, tenderness, fever, malaise and worsening swelling requires prompt antibiotic treatment and sepsis assessment.
Investigation priorities
01
First-line standardised limb or breast measurementFirst stepFirst line
Confirm asymmetry, establish a baseline and track response using circumference, calculated volume, perometry or bioimpedance.
02
First-line venous duplex for acute arm swellingFirst line
Exclude axillary and upper-arm DVT when onset, pain, catheter or venous signs are atypical for chronic lymphoedema.
Management branches
New swellingExclude urgent mimics before compression
An arm, breast or chest wall becomes newly or rapidly swollen after breast-cancer treatment.
Assess onset, fever, pain, colour, venous collaterals, catheter, nodes, respiratory symptoms and cancer history and compare both limbs and central venous territories.
Obtain urgent duplex and central imaging for suspected thrombosis, antibiotics for cellulitis and cross-sectional imaging with biopsy for possible recurrence.
Key medicines
Flucloxacillin for lymphoedema-associated cellulitisFor a stable adult with non-purulent cellulitis and no immediate penicillin allergy, a common lymphoedema regimen is flucloxacillin 500 mg orally four times daily for 14 days, adjusted to severity, culture and local guidance.
Phenoxymethylpenicillin prophylaxisAfter recurrent proven cellulitis, a specialist protocol may use phenoxymethylpenicillin 250 mg orally twice daily, often 500 mg twice daily when BMI is 33 kg/m² or higher, with duration reviewed after at least 12 months.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.