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

Recommended Dose of Cephalexin for Cellulitis

For adults with uncomplicated cellulitis, cephalexin 500 mg orally four times daily (every 6 hours) for 5 days is the recommended regimen, with treatment extended only if the infection has not improved within this timeframe. 1

Standard Dosing Protocol

• Cephalexin 500 mg every 6 hours (four times daily) is the standard oral regimen endorsed by the Infectious Diseases Society of America for typical non-purulent cellulitis in adults 2, 1
• The FDA-approved adult dosage range is 1 to 4 grams daily in divided doses, with 250 mg every 6 hours as the usual adult dose, though 500 mg every 12 hours may be administered for skin and skin structure infections 3
• Treatment duration should be 5 days if clinical improvement occurs, as this is as effective as 10-day courses for uncomplicated cellulitis 1

When to Consider Higher Doses

• A pilot randomized controlled trial in 2023 demonstrated that high-dose cephalexin (1000 mg four times daily) resulted in fewer treatment failures (3.2%) compared to standard-dose 500 mg (12.9% failure rate), though with a higher proportion of minor adverse effects 4
• For more severe infections or those caused by less susceptible organisms, larger doses may be needed, but if daily doses greater than 4 grams are required, parenteral cephalosporins should be considered 3

Clinical Context and Appropriateness

• Cephalexin is the oral agent of choice for cellulitis caused by methicillin-susceptible Staphylococcus aureus and streptococci 1
• MRSA coverage is NOT routinely needed for typical non-purulent cellulitis—β-lactam monotherapy with cephalexin is appropriate in the absence of abscess, ulcer, or purulent drainage 1
• Adding trimethoprim-sulfamethoxazole to cephalexin does not improve outcomes in uncomplicated cellulitis without abscess 5

Important Caveats

• Do NOT extend treatment beyond 5 days unless there is lack of clinical improvement—unnecessary prolongation offers no additional benefit 1
• Consider MRSA coverage (and thus alternative antibiotics) ONLY if cellulitis is associated with penetrating trauma, evidence of MRSA infection elsewhere, purulent drainage, injection drug use, or systemic inflammatory response syndrome 1, 6
• For penicillin-allergic patients (except those with immediate hypersensitivity), cephalexin remains an option due to low cross-reactivity 1
• If true cephalosporin allergy exists, clindamycin 300-450 mg orally four times daily is the preferred alternative 6

Adjunctive Measures

• Elevation of the affected extremity is essential to promote drainage of edema and inflammatory substances 6
• Identify and treat predisposing conditions such as tinea pedis (toe web abnormalities), venous insufficiency, lymphedema, eczema, and obesity 2, 1
• Examine interdigital toe spaces in lower-extremity cellulitis, as treating fissuring or maceration may reduce recurrence 1

When to Escalate Care

• Consider hospitalization if there is concern for deeper or necrotizing infection, poor adherence to therapy, severe immunocompromise, or outpatient treatment failure 1, 6
• Prompt surgical consultation is needed for aggressive infections with signs of systemic toxicity or suspicion of necrotizing fasciitis 2