What is the recommended dose for cellulitis treatment?

Recommended Doses for Cellulitis Treatment

For outpatient non-purulent cellulitis, use cephalexin 500 mg four times daily or dicloxacillin 500 mg four times daily for 5 days; for purulent cellulitis or MRSA risk, use trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily or clindamycin 300-450 mg four times daily for 5-10 days; for hospitalized severe cellulitis, use vancomycin 15 mg/kg every 12 hours IV or ceftaroline 600 mg every 12 hours IV for 7-14 days. 1, 2, 3

Outpatient Dosing by Clinical Presentation

Non-Purulent Cellulitis (No Drainage/Abscess)

Target beta-hemolytic streptococci as the primary pathogen 1:

First-line options:

• Cephalexin 500 mg four times daily PO 1
• Dicloxacillin 500 mg four times daily PO 1
• Penicillin VK 250-500 mg every 6 hours PO 1

Duration: 5 days minimum, extending if no improvement 1

Purulent Cellulitis (With Drainage but No Drainable Abscess)

Empiric MRSA coverage is essential 1:

Preferred oral options:

• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
• Clindamycin 300-450 mg four times daily 1
• Doxycycline 100 mg twice daily (avoid in children <8 years) 1
• Linezolid 600 mg twice daily 1

Duration: 5-10 days based on clinical response 1

Dual Coverage (Streptococci + MRSA)

When both pathogens are suspected 1:

• Clindamycin 300-450 mg four times daily alone 1
• TMP-SMX 1-2 double-strength tablets twice daily PLUS amoxicillin 1
• Doxycycline 100 mg twice daily PLUS a beta-lactam 1

Hospitalized/Severe Cellulitis Dosing

For Complicated or Severe Infections

IV vancomycin is the first-line choice for severe cellulitis with systemic signs 2, 3:

• Vancomycin 15 mg/kg every 12 hours IV 1, 2, 3
• Ceftaroline 600 mg every 12 hours IV 1, 2
• Linezolid 600 mg every 12 hours IV or PO 1
• Daptomycin 4 mg/kg once daily IV 1
• Clindamycin 600-900 mg every 6-8 hours IV 1

For Non-Purulent Cellulitis Without MRSA Risk

• Cefazolin 1 g every 8 hours IV 1
• Nafcillin 1-2 g every 4-6 hours IV 1, 2

Duration: 7-14 days for severe infections, with modification to MRSA-active therapy if no clinical response 1, 3

Pediatric Dosing

Outpatient Pediatric Doses

• Cephalexin 25-50 mg/kg/day in 4 divided doses 1
• TMP-SMX 8-12 mg/kg/day (based on trimethoprim) in 2-4 divided doses 1
• Avoid tetracyclines in children <8 years 1

Hospitalized Pediatric Doses

• Vancomycin 40 mg/kg/day in 4 divided doses IV 1
• Clindamycin 10-13 mg/kg/dose every 6-8 hours IV (40 mg/kg/day total) if local clindamycin resistance <10% 1
• Linezolid 10 mg/kg/dose every 8 hours for children <12 years; 600 mg twice daily for ≥12 years 1

Critical Decision Points

When to Add MRSA Coverage

Add empiric MRSA coverage in outpatients with 1:

• Purulent drainage without drainable abscess
• Failure to respond to beta-lactam therapy
• Systemic toxicity present
• Known MRSA risk factors (athletes, prisoners, IV drug users, prior MRSA) 4

When to Hospitalize

Admit patients with 1, 2:

• SIRS criteria or hemodynamic instability
• Altered mental status
• Concern for necrotizing infection
• Severe immunocompromise
• Failed outpatient therapy

Treatment Duration Algorithm

• Mild outpatient cellulitis: 5 days minimum 1, 2
• Moderate outpatient cellulitis: 5-10 days 1
• Severe hospitalized cellulitis: 7-14 days 1, 3
• Extend duration if no improvement at initial endpoint 1

Common Pitfalls

Avoid these errors:

• Using rifampin as monotherapy or adjunctive therapy (not recommended) 1
• Prescribing tetracyclines to children <8 years 1
• Failing to cover MRSA in purulent cellulitis 1
• Inadequate treatment duration in severe infections 3
• Using clindamycin in areas with >10% erythromycin resistance without susceptibility testing 1