Cephalexin Dosing for Cellulitis
For non-purulent cellulitis in adults, cephalexin should be dosed at 500 mg orally four times daily (every 6 hours) for 5-7 days. 1, 2
Standard Dosing Recommendations
- For adults with typical cellulitis, the recommended dose is 500 mg orally four times daily (every 6 hours) 3, 1
- For children, the recommended dose is 25-50 mg/kg/day divided into four doses 2
- The standard duration of therapy is 5 days for uncomplicated cellulitis, but should be extended if the infection has not adequately improved within this timeframe 1
- For more severe infections, the adult dosage may be increased up to 4 g daily in divided doses 2
Clinical Considerations
- Cephalexin is the oral agent of choice for treating cellulitis caused by methicillin-susceptible Staphylococcus aureus (MSSA) and streptococci 1, 3
- For non-purulent cellulitis without systemic signs of infection, oral antibiotics like cephalexin are appropriate for outpatient management 1
- 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
- Recent research shows that adding trimethoprim-sulfamethoxazole to cephalexin does not improve outcomes in uncomplicated cellulitis 4, 5
Special Situations
- 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
- For penicillin-allergic patients (except those with immediate hypersensitivity reactions), cephalexin remains an option 1, 3
- A pilot study 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 more minor adverse effects 6
- In severe infections requiring hospitalization, parenteral antibiotics should be considered 2
Adjunctive Measures
- Elevation of the affected area is important to promote gravity drainage of edema and inflammatory substances 3
- Treatment of predisposing factors (such as edema, tinea pedis, or venous insufficiency) is essential for preventing recurrence 1, 3
- For non-diabetic adult patients without other contraindications, systemic corticosteroids may be considered as they can attenuate the inflammatory response and hasten resolution 1, 3
- Some evidence suggests that adding anti-inflammatory therapy (such as ibuprofen) to antibiotic treatment may hasten resolution of cellulitis-related inflammation 7
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, 3
- 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 1, 3
- Don't neglect to consider hospitalization if there is concern for deeper infection, poor adherence to therapy, immunocompromise, or if outpatient treatment is failing 1