What is the recommended dose and frequency of cephalexin (cephalexin) for treating cellulitis?

Cephalexin Dosing for Cellulitis

For adult patients with cellulitis, the recommended dose of cephalexin is 500 mg orally four times daily (every 6 hours) for 5 days, with extension of therapy if the infection has not improved within this time period. 1, 2

Standard Adult Dosing Regimen

• The Infectious Diseases Society of America (IDSA) recommends cephalexin 500 mg four times daily as the standard oral regimen for typical non-purulent cellulitis 1
• FDA-approved dosing for skin and skin structure infections is 500 mg every 12 hours, though for more severe infections, larger doses (up to 4g daily) may be needed 3
• The usual duration of therapy is 5 days, but treatment should be extended if clinical improvement has not occurred 2, 1
• Recent research suggests high-dose cephalexin (1000 mg four times daily) may result in fewer treatment failures compared to standard dosing (500 mg four times daily), though with slightly more minor adverse effects 4

Pediatric Dosing Regimen

• For children, the recommended daily dosage is 25-50 mg/kg divided into four doses 3
• For skin and skin structure infections in pediatric patients, the total daily dose may alternatively be divided and administered every 12 hours 3
• In severe infections, the pediatric dosage may be doubled 3

Clinical Considerations

• Cephalexin is the oral agent of choice for treating cellulitis caused by methicillin-susceptible Staphylococcus aureus (MSSA) and streptococci 1
• For non-purulent cellulitis without systemic signs of infection, oral antibiotics like cephalexin are appropriate for outpatient management 1, 2
• MRSA is an unusual cause of typical cellulitis - β-lactam monotherapy with cephalexin is recommended in the absence of abscess, ulcer, or purulent drainage 1
• Adding trimethoprim-sulfamethoxazole to cephalexin does not improve outcomes in patients with non-purulent cellulitis 5

Special Situations

• Hospitalization should be considered if there is concern for deeper infection, poor adherence to therapy, immunocompromise, or if outpatient treatment is failing 2, 1
• For cellulitis associated with penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, or injection drug use, consider adding coverage for MRSA 1
• Elevation of the affected area and treatment of predisposing factors (such as edema, tinea pedis, or venous insufficiency) are important adjunctive measures 2, 1
• For non-diabetic adult patients, systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered as they may attenuate the inflammatory response 2, 1

Common Pitfalls to Avoid

• Don't extend treatment unnecessarily - 5 days is as effective as 10 days for uncomplicated cellulitis if clinical improvement has occurred 1
• Don't overlook underlying conditions that may predispose to recurrent cellulitis (tinea pedis, venous insufficiency, lymphedema) 1
• Don't automatically add MRSA coverage for typical non-purulent cellulitis without risk factors for MRSA 1
• Don't forget to examine interdigital toe spaces in lower-extremity cellulitis, as treating fissuring or maceration may reduce recurrence 2
• Don't miss the opportunity to consider once-daily dosing alternatives in appropriate cases - some studies suggest once-daily cefadroxil may be as effective as four-times-daily cephalexin for certain odontogenic infections 6