What is the recommended dose of Cephalexin (Cefalexin) for the treatment of cellulitis?

Cephalexin Dosing for Cellulitis

For adult patients with cellulitis, the recommended dose of cephalexin is 500 mg four times daily (every 6 hours) for 5-7 days. 1, 2

Adult Dosing Regimen

• Standard oral regimen: 500 mg every 6 hours (2 g total daily dose) 1, 3
• Duration: 5 days is typically sufficient if clinical improvement occurs, though treatment may be extended if infection has not adequately improved 1, 3
• For more severe infections, doses up to 4 g daily may be considered 2

Pediatric Dosing Regimen

• Standard dose: 75-100 mg/kg/day divided into 3-4 doses 2
• For typical skin infections: 25-50 mg/kg/day divided into 4 doses 2
• For severe infections, dosage may be doubled 2

Clinical Decision Algorithm

1. Assess severity and type of cellulitis:

   • For typical non-purulent cellulitis without systemic signs: oral cephalexin is appropriate 1, 3
   • For purulent cellulitis or evidence of abscess: consider additional MRSA coverage 3
   • For severe infection with systemic signs: consider intravenous therapy 3

2. Determine appropriate duration:

   • Start with 5-day course 1, 3
   • Extend treatment if no clinical improvement by day 5 1
   • Continue therapy until 3 days after the infection appears cured 4

3. Consider adjunctive measures:

   • Elevation of affected area to promote drainage of edema 3
   • Treatment of predisposing conditions (tinea pedis, venous insufficiency) 3, 1
   • For non-diabetic adults, systemic corticosteroids may be considered (prednisone 40 mg daily for 7 days) 3, 1

Evidence Strength and Considerations

• MRSA is an unusual cause of typical cellulitis - β-lactam monotherapy with cephalexin is appropriate in the absence of abscess, ulcer, or purulent drainage 1, 3
• Recent randomized trials show that adding trimethoprim-sulfamethoxazole (for MRSA coverage) to cephalexin does not significantly improve outcomes for uncomplicated cellulitis 4, 5
• A recent pilot study suggests high-dose cephalexin (1000 mg four times daily) may reduce treatment failure compared to standard dosing (500 mg four times daily), though with more minor adverse effects 6
• Adding anti-inflammatory therapy (such as ibuprofen) to antibiotic treatment may hasten resolution of cellulitis-related inflammation 7

Common Pitfalls to Avoid

• Don't automatically add MRSA coverage for typical non-purulent cellulitis without specific risk factors for MRSA 1, 3
• Don't extend treatment unnecessarily beyond 5-7 days if clinical improvement has occurred 1, 3
• Don't overlook examining interdigital toe spaces in lower-extremity cellulitis, as treating fissuring or maceration may reduce recurrence 1
• Don't forget to consider hospitalization if there is concern for deeper infection, poor adherence to therapy, immunocompromise, or if outpatient treatment is failing 1

Special Situations

• For cellulitis associated with penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, or injection drug use: consider adding MRSA coverage 1, 3
• For recurrent cellulitis: address predisposing factors and consider prophylactic antibiotics for patients with 3-4 episodes per year 3
• For penicillin-allergic patients (except those with immediate hypersensitivity reactions), cephalexin remains an option 1