Cephalexin Dosing for Wound Infections
For wound infections in adults, cephalexin should be dosed at 500 mg orally four times daily (every 6 hours) for 7-10 days. 1, 2
Adult Dosing Recommendations
Standard dose: 500 mg orally four times daily (every 6 hours) is the recommended regimen for skin and soft tissue infections, including wound infections caused by methicillin-susceptible Staphylococcus aureus (MSSA). 1, 2
For mild to moderate infections, the dose may be reduced to 250 mg every 6 hours, though 500 mg four times daily provides more reliable coverage for wound infections. 1, 2
The FDA-approved dosage range for adults is 1-4 grams daily in divided doses, with the usual adult dose being 250 mg every 6 hours for most infections. 2
Duration of therapy is typically 7-10 days, depending on clinical response and severity of infection. 1
Pediatric Dosing Recommendations
For children with mild to moderate wound infections: 25-50 mg/kg/day divided into 4 doses (every 6 hours). 1, 2
For MSSA infections in children: 75-100 mg/kg/day divided into 3-4 doses provides more aggressive coverage when staphylococcal infection is confirmed or strongly suspected. 1, 2
The total daily dose may be divided and administered every 12 hours for skin and skin structure infections in patients over 1 year of age. 2
Clinical Considerations for Wound Infections
When Cephalexin is Appropriate
Cephalexin is effective for uncomplicated wound infections caused by MSSA and streptococci. 3, 4
A randomized controlled trial demonstrated that cephalexin 500 mg four times daily was non-inferior to intravenous cefazolin for uncomplicated mild-moderate skin and soft tissue infections, with treatment failure rates of only 4.2% at 72 hours. 3
Important Limitations
Cephalexin is completely ineffective against MRSA and should not be used if methicillin-resistant S. aureus is suspected or confirmed. 1
Cephalexin has poor activity against Haemophilus influenzae, Moraxella catarrhalis, and is completely ineffective against Pseudomonas aeruginosa. 1
For bite wounds (animal or human), cephalexin alone is NOT recommended as first-line therapy because it misses important pathogens like Pasteurella multocida (animal bites) and Eikenella corrodens (human bites), and has inadequate anaerobic coverage. 5
Special Wound Types Requiring Alternative Antibiotics
Animal bite wounds: Use amoxicillin-clavulanate 875/125 mg twice daily as first-line therapy to cover both aerobic and anaerobic bacteria. 5
Human bite wounds: Use amoxicillin-clavulanate 875/125 mg twice daily or ampicillin-sulbactam 1.5-3.0 g IV every 6 hours to cover Eikenella corrodens and anaerobes. 5
High-risk wounds (immunocompromised patients, asplenic, advanced liver disease, hand/face injuries, or wounds penetrating periosteum/joint capsule) require preemptive antimicrobial therapy for 3-5 days with agents covering both aerobes and anaerobes. 5
Penicillin Allergy Considerations
- Cephalexin can be used in patients with non-severe penicillin allergy, but is contraindicated in patients with a history of anaphylaxis, angioedema, or urticaria to penicillins. 1