When should a patient with cellulitis be admitted to the hospital?

When to Admit a Cellulitis Patient

Admit patients with cellulitis who have signs of systemic inflammatory response syndrome (SIRS), hemodynamic instability, altered mental status, suspicion of necrotizing infection, severe immunosuppression, or failure of outpatient treatment. 1

Absolute Indications for Hospitalization

These patients require immediate admission:

• Presence of SIRS criteria (fever, tachycardia, tachypnea, leukocytosis) 1
• Hemodynamic instability including hypotension or signs of shock 1, 2
• Altered mental status or confusion 1, 2
• Signs of necrotizing infection such as severe pain disproportionate to exam, crepitus, bullae, skin necrosis, gangrene, or ecchymoses 1, 2
• Metabolic instability including severe hyperglycemia, acidosis, new azotemia, or electrolyte abnormalities 3, 2

Relative Indications for Hospitalization

Consider admission for patients with these features:

• Extensive cellulitis with erythema extending >2 cm from the wound edge (some sources suggest >5 cm or >12 cm as thresholds) 3, 1, 2
• Rapidly progressive erythema or acute worsening of infection 3, 1
• Lymphangitic streaking indicating spreading infection 3, 2
• Deep tissue involvement including penetration to fascia, tendon, muscle, joint, or bone 3, 2
• Severe immunosuppression (note that immunosuppressed patients may not mount robust inflammatory responses but still have severe infection) 1
• Critical limb ischemia or severe peripheral arterial disease 3, 2
• Abscess requiring surgical drainage 2
• Need for intravenous antibiotic therapy when home parenteral programs are unavailable 3, 1
• Poor anticipated adherence or inability to follow up within 48-72 hours 1, 2
• Failure of outpatient treatment with progression despite appropriate antibiotics 3, 1

Special Considerations for High-Risk Populations

Diabetic Patients with Foot Cellulitis

Consider hospitalization for all diabetic patients with severe foot infections or moderate infections with key comorbidities, particularly peripheral arterial disease. 3

• Diabetic foot infections carry higher risk of amputation and death 3
• The presence of osteomyelitis alone does not mandate admission if the patient is clinically stable and can receive oral antibiotics 3
• Diabetic patients require closer monitoring of glycemic control during infection 2

Predictive Factors for Admission Failure

Research has identified specific factors predicting failure of observation unit management:

• Cellulitis of the hand (odds ratio 2.9) 4
• Fever >100.4°F (odds ratio 2.5) 4
• Lactate >2 mmol/L (odds ratio 3.1) 4

Patients Safe for Outpatient Management

These patients can typically be managed as outpatients:

• Limited cellulitis with erythema extending <2 cm around the wound 2
• Superficial infection limited to skin or superficial subcutaneous tissues 2
• No systemic symptoms or metabolic instability 2
• Reliable follow-up capability within 48-72 hours 1, 2
• Ability to take oral antibiotics and comply with treatment 3

Critical Pitfalls to Avoid

• Failing to recognize early necrotizing infection signs (severe pain, crepitus, necrotic skin) which requires urgent surgical evaluation 1
• Underestimating disease severity in immunosuppressed patients who may not show typical inflammatory responses 1
• Missing systemic toxicity signs in diabetic or elderly patients who may present atypically 2
• Failing to ensure adequate follow-up as outpatient treatment can silently fail without reevaluation within 48-72 hours 1, 2
• Delaying surgical consultation for deep space infections or abscess formation 2
• Overlooking critical limb ischemia which significantly worsens prognosis 2

Follow-Up Requirements for Outpatient Management

All outpatients must have:

• Reevaluation within 48-72 hours to assess response to therapy 2
• Clear instructions to return immediately if symptoms worsen or systemic signs develop 1
• Consideration for antibiotic change if no improvement after 48 hours 2