What is the dose for uncomplicated cellulitis?

Antibiotic Dosing for Uncomplicated Cellulitis

For uncomplicated cellulitis, use a 5-day course of antibiotics active against streptococci, with specific dosing recommendations as follows: cephalexin 500 mg every 6 hours, dicloxacillin 500 mg four times daily, clindamycin 300-450 mg four times daily, or amoxicillin-clavulanate 875/125 mg twice daily. 1

First-Line Antibiotic Options and Dosing

Standard Regimens (Streptococcal Coverage)

• Cephalexin: 500 mg orally every 6 hours for 5 days 1
• Dicloxacillin: 500 mg orally four times daily for 5 days 1, 2
• Penicillin VK: 250-500 mg orally every 6 hours for 5 days 1
• Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5 days 1
• Clindamycin: 300-450 mg orally four times daily for 5 days 1

Duration of Therapy

• A 5-day course is recommended for uncomplicated cellulitis 1, 3
• Treatment should be extended if the infection has not improved within this time period 1
• Multiple studies have shown that 5-6 days of therapy is as effective as 10 days for uncomplicated cellulitis 1, 3

Alternative Regimens for Special Circumstances

MRSA Coverage (when indicated)

• Trimethoprim-sulfamethoxazole: 1-2 double-strength tablets (160/800 mg) twice daily for 5 days 1, 4
• Doxycycline: 100 mg twice daily for 5 days 1
• Linezolid: 600 mg twice daily for 5 days 1

When to Consider MRSA Coverage

• Cellulitis associated with penetrating trauma 1
• Evidence of MRSA infection elsewhere 1
• Nasal colonization with MRSA 1
• Injection drug use 1
• Systemic inflammatory response syndrome (SIRS) 1

Severe Infections Requiring IV Therapy

• Vancomycin: 15-20 mg/kg/dose IV every 8-12 hours 1
• Cefazolin: 1 g IV every 8 hours 1
• Clindamycin: 600-900 mg IV every 8 hours 1

Clinical Decision-Making Algorithm

1. Assess severity of infection:

   • Mild (no systemic signs): Oral therapy with streptococcal coverage 1
   • Moderate (systemic signs): Consider broader coverage including MSSA 1
   • Severe (SIRS or high-risk features): IV therapy with MRSA coverage 1

2. Evaluate risk factors for MRSA:

   • If risk factors present: Add MRSA coverage 1
   • If no risk factors: Standard streptococcal coverage is sufficient 1, 2

3. Reassess at day 5:

   • If improved: Complete 5-day course 1, 3
   • If not improved: Extend therapy and consider alternative diagnosis or antibiotic 1

Important Clinical Pearls

• Blood cultures are not routinely recommended for typical cellulitis 1
• Elevation of the affected area is an important adjunctive measure 2
• Treat any predisposing conditions such as tinea pedis or venous eczema 2
• Recent studies show no benefit to adding trimethoprim-sulfamethoxazole to cephalexin for uncomplicated cellulitis 5, 6

Common Pitfalls

• Overuse of antibiotics targeting MRSA when not indicated 1, 2
• Unnecessarily prolonged antibiotic courses beyond 5 days when clinical improvement is evident 1, 3
• Failure to address underlying predisposing conditions 2
• Misdiagnosis of deep tissue infections or purulent infections as simple cellulitis 1, 7