Cellulitis / soft-tissue infection
A streamlined, differential-led presentation for rapid clinical review.
Twenty-second review
- Cellulitis is infection of skin and subcutaneous tissue causing local inflammation; deeper or rapidly spreading infection can cause tissue necrosis and systemic illness.
- Pain out of proportion, rapid spread, bullae, crepitus, hypotension, confusion, immune compromise, or involvement near a device is high risk.
- Keep dvt, venous stasis, or allergic reaction in the differential; overlapping or concurrent illness remains possible.
- For cellulitis / soft-tissue infection, trends and combinations of findings are more informative than one isolated vital sign.
Compare the clinical patterns
The repeated material is grouped inside each possibility. Open only the condition you need.
Necrotizing infectionTime-sensitive high-risk possibility
HPI
Clarify location and onset; spread, redness or swelling; pain out of proportion.
Signs & symptoms
Disproportionate pain, toxicity, rapid progression, bullae, crepitus, or shock.
Focused exam
Assess skin, hydration, respiratory findings, abdomen, urinary symptoms, wounds, lines, and mental status as relevant; Repeat temperature and perfusion observations; obtain collateral baseline information.
Brief pathophysiology
Necrotizing infection may cause cellulitis / soft-tissue infection through a time-sensitive process capable of rapid physiological deterioration.
What the trend may show
Isolated musculoskeletal injury often leaves central vital signs near baseline. Persistent abnormality should prompt reassessment for hemorrhage, thoracic injury, infection, or a medical cause.
Heart rate (bpm)
May rise with painTachycardia can reflect pain or distress; trend after treatment.
Blood pressure (mmHg)
May rise with painHypotension is not expected in an isolated minor injury.
Respiratory rate (breaths/min)
May rise with painPersistent tachypnea suggests more than a minor isolated injury.
Oxygen saturation (SpO₂)
Usually preservedDesaturation suggests thoracic injury or concurrent disease.
Front-load in the triage report
- Necrotizing infection: Disproportionate pain, toxicity, rapid progression, bullae, crepitus, or shock.
- Location and onset?
- Spread, redness or swelling?
SepsisTime-sensitive high-risk possibility
HPI
Clarify spread, redness or swelling; pain out of proportion; fever or systemic symptoms.
Signs & symptoms
Disproportionate pain, toxicity, rapid progression, bullae, crepitus, or shock.
Focused exam
Repeat temperature and perfusion observations; obtain collateral baseline information; Mark or describe borders when appropriate; assess warmth, tenderness, edema, wounds, fluctuance, necrosis, lymphangitis, and distal function.
Brief pathophysiology
Sepsis may cause cellulitis / soft-tissue infection through a time-sensitive process capable of rapid physiological deterioration.
What the trend may show
No single vital sign diagnoses sepsis. New tachypnea, abnormal temperature, tachycardia, or falling pressure—especially with altered mentation or poor perfusion—supports organ dysfunction and urgency.
Respiratory rate (breaths/min)
May rise earlyTachypnea is included in NEWS2 and can precede overt hypotension.
Temperature (°C)
High or lowAbsence of fever does not exclude sepsis; hypothermia is concerning.
Heart rate (bpm)
Often risesTachycardia is common but may be blunted by age or medication.
Blood pressure (mmHg)
May fallRelative hypotension and trend matter; profound hypotension can be late.
Front-load in the triage report
- Sepsis: Disproportionate pain, toxicity, rapid progression, bullae, crepitus, or shock.
- Spread, redness or swelling?
- Pain out of proportion?
Uncomplicated cellulitisCommon presentation pattern
HPI
Clarify location and onset; spread, redness or swelling; pain out of proportion.
Signs & symptoms
Local warmth, erythema, tenderness, and a skin entry point may fit.
Focused exam
Assess skin, hydration, respiratory findings, abdomen, urinary symptoms, wounds, lines, and mental status as relevant; Repeat temperature and perfusion observations; obtain collateral baseline information.
Brief pathophysiology
Uncomplicated cellulitis may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.
What the trend may show
Isolated musculoskeletal injury often leaves central vital signs near baseline. Persistent abnormality should prompt reassessment for hemorrhage, thoracic injury, infection, or a medical cause.
Heart rate (bpm)
May rise with painTachycardia can reflect pain or distress; trend after treatment.
Blood pressure (mmHg)
May rise with painHypotension is not expected in an isolated minor injury.
Respiratory rate (breaths/min)
May rise with painPersistent tachypnea suggests more than a minor isolated injury.
Oxygen saturation (SpO₂)
Usually preservedDesaturation suggests thoracic injury or concurrent disease.
Front-load in the triage report
- Local warmth, erythema, tenderness, and a skin entry point may fit.
- Location and onset?
- Spread, redness or swelling?
DVTImportant alternative presentation
HPI
Clarify location and onset; spread, redness or swelling; pain out of proportion.
Signs & symptoms
Swelling and redness can have noninfectious causes.
Focused exam
Assess skin, hydration, respiratory findings, abdomen, urinary symptoms, wounds, lines, and mental status as relevant; Repeat temperature and perfusion observations; obtain collateral baseline information.
Brief pathophysiology
DVT can resemble cellulitis / soft-tissue infection through overlapping symptoms or referred physiology despite a different primary mechanism.
What the trend may show
Pulmonary embolism may have normal observations. Tachycardia, tachypnea, or hypoxemia increase concern; hypotension identifies hemodynamic compromise rather than being required for diagnosis.
Heart rate (bpm)
May riseTachycardia is common but neither sensitive nor specific.
Respiratory rate (breaths/min)
May riseTachypnea may be an early sign of increased ventilatory demand.
Oxygen saturation (SpO₂)
May fallHypoxemia may occur, but a normal saturation does not exclude PE.
Blood pressure (mmHg)
Often preservedHypotension suggests high-risk PE with obstructive shock.
Front-load in the triage report
- Swelling and redness can have noninfectious causes.
- Location and onset?
- Spread, redness or swelling?
Venous stasisImportant alternative presentation
HPI
Clarify spread, redness or swelling; pain out of proportion; fever or systemic symptoms.
Signs & symptoms
Swelling and redness can have noninfectious causes.
Focused exam
Repeat temperature and perfusion observations; obtain collateral baseline information; Mark or describe borders when appropriate; assess warmth, tenderness, edema, wounds, fluctuance, necrosis, lymphangitis, and distal function.
Brief pathophysiology
Venous stasis can resemble cellulitis / soft-tissue infection through overlapping symptoms or referred physiology despite a different primary mechanism.
What the trend may show
Isolated musculoskeletal injury often leaves central vital signs near baseline. Persistent abnormality should prompt reassessment for hemorrhage, thoracic injury, infection, or a medical cause.
Heart rate (bpm)
May rise with painTachycardia can reflect pain or distress; trend after treatment.
Blood pressure (mmHg)
May rise with painHypotension is not expected in an isolated minor injury.
Respiratory rate (breaths/min)
May rise with painPersistent tachypnea suggests more than a minor isolated injury.
Oxygen saturation (SpO₂)
Usually preservedDesaturation suggests thoracic injury or concurrent disease.
Front-load in the triage report
- Swelling and redness can have noninfectious causes.
- Spread, redness or swelling?
- Pain out of proportion?
Allergic reactionImportant alternative presentation
HPI
Clarify pain out of proportion; fever or systemic symptoms; wound, bite or procedure.
Signs & symptoms
Swelling and redness can have noninfectious causes.
Focused exam
Repeat temperature and perfusion observations; obtain collateral baseline information; Mark or describe borders when appropriate; assess warmth, tenderness, edema, wounds, fluctuance, necrosis, lymphangitis, and distal function.
Brief pathophysiology
Allergic reaction can resemble cellulitis / soft-tissue infection through overlapping symptoms or referred physiology despite a different primary mechanism.
What the trend may show
Isolated musculoskeletal injury often leaves central vital signs near baseline. Persistent abnormality should prompt reassessment for hemorrhage, thoracic injury, infection, or a medical cause.
Heart rate (bpm)
May rise with painTachycardia can reflect pain or distress; trend after treatment.
Blood pressure (mmHg)
May rise with painHypotension is not expected in an isolated minor injury.
Respiratory rate (breaths/min)
May rise with painPersistent tachypnea suggests more than a minor isolated injury.
Oxygen saturation (SpO₂)
Usually preservedDesaturation suggests thoracic injury or concurrent disease.
Front-load in the triage report
- Swelling and redness can have noninfectious causes.
- Pain out of proportion?
- Fever or systemic symptoms?
Findings that should escalate concern
- Rapid progression
- Crepitus
- Shock
- Severe pain out of proportion
- Pain out of proportion, rapid spread, bullae, crepitus, hypotension, confusion, immune compromise, or involvement near a device is high risk.
- Necrotizing infection or sepsis: Disproportionate pain, toxicity, rapid progression, bullae, crepitus, or shock.
Medication recognition
Continue the clinical pathway
Clinical and academic sources
Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.
BCEHS Handbook — specific CPGs
- A02: Patient AssessmentBC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for patient assessment.
- K01: Infectious Diseases (General)BC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for infectious diseases (general).
Supporting clinical and academic evidence
- CEDIS Presenting Complaint List updateCanadian Association of Emergency Physicians
Presenting-complaint terminology and categorization context. It does not establish a prehospital “top 100” ranking.
- Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2026Society of Critical Care Medicine and European Society of Intensive Care Medicine
Contemporary sepsis physiology, perfusion, and hemodynamic context. Hospital treatment recommendations do not replace BCEHS guidance.
- Suspected sepsis in people aged 16 or over: recognition, assessment and early managementNational Institute for Health and Care Excellence
Recognition, early assessment, monitoring, risk, and limitations of isolated observations in suspected adult sepsis.
- Canadian Emergency Department Best Practices Checklist for Skin and Soft Tissue Infections: CellulitisCJEM · 2024
Cellulitis recognition, mimics, severity, systemic illness, and evidence-based emergency care.