Keflex (Cephalexin) Dosing for Cellulitis

For adults with cellulitis, the recommended dose of Keflex (cephalexin) is 500 mg orally four times daily (2 grams total daily dose). 1, 2

Adult Dosing Recommendations

For typical non-purulent cellulitis, cephalexin 500 mg four times daily (every 6 hours) is the standard oral regimen 1
The usual duration of therapy is 5 days, but treatment should be extended if the infection has not improved within this time period 1
For more severe infections, the dose may be increased up to 4 grams daily in divided doses 2
Some clinicians use 1000 mg four times daily for more severe cases, which may reduce treatment failure rates compared to standard dosing (12.9% vs 3.2% failure rates in one study) 3

For children, the recommended dose is 25-50 mg/kg/day divided into four equal doses 1, 2
For skin and skin structure infections in children over 1 year of age, the total daily dose may be divided and administered every 12 hours 2

Cephalexin is the oral agent of choice for treating cellulitis caused by methicillin-susceptible strains of Staphylococcus aureus and streptococci 1
For patients with 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
Hospitalization should be considered if there is concern for deeper infection, poor adherence to therapy, immunocompromise, or if outpatient treatment is failing 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
For penicillin-allergic patients (except those with immediate hypersensitivity reactions), cephalexin remains an option 1
Elevation of the affected area and treatment of predisposing factors (such as edema, tinea pedis, or venous insufficiency) are important adjunctive measures 1

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 1

Patients should show signs of improvement within 48-72 hours of starting appropriate therapy 4
Consider adjunctive anti-inflammatory therapy (such as ibuprofen) which may hasten resolution of inflammation 4
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 1