Recommended Cephalexin Dosing for Uncomplicated Wound Infections
For uncomplicated wound infections in adults, cephalexin 500 mg every 6 hours (four times daily) is the standard recommended dose, though 500 mg every 12 hours (twice daily) is an acceptable alternative for less severe infections. 1
Dosing Regimens
The FDA-approved dosing for cephalexin provides two options for skin and soft tissue infections:
- Standard dosing: 250 mg every 6 hours (four times daily)
- Alternative dosing for uncomplicated infections: 500 mg every 12 hours (twice daily) 1
For more severe infections or those caused by less susceptible organisms, larger doses may be needed, with the maximum adult dose being 4 grams daily in divided doses 1.
Clinical Context and Evidence
The 2014 IDSA guidelines for skin and soft tissue infections list cephalexin as an appropriate oral agent for methicillin-susceptible Staphylococcus aureus (MSSA) infections at 500 mg four times daily 2. This aligns with the drug label recommendations.
Multiple clinical trials demonstrate excellent efficacy with standard cephalexin dosing. Studies show clinical cure rates exceeding 95% for uncomplicated skin and soft tissue infections when using either 250 mg four times daily or 500 mg twice daily regimens 3, 4. A comparative study found 500 mg twice daily cephalexin achieved 94% clinical cure rates for wound infections 5.
Duration of Therapy
Treatment duration should typically be 7-10 days for uncomplicated wound infections 1. This is consistent across the FDA labeling and clinical practice guidelines.
Important Considerations
Cephalexin lacks activity against MRSA, despite some clinical studies showing apparent response in MRSA-infected wounds 5. These responses likely reflect the contribution of incision and drainage rather than antibiotic activity. If MRSA is suspected or confirmed, alternative agents with proven MRSA activity should be used 2.
The drug is active against:
- Staphylococcus aureus (MSSA only, including penicillinase-producing strains)
- Streptococcus pyogenes and S. pneumoniae (penicillin-susceptible)
- Common gram-negative organisms (E. coli, Klebsiella, Proteus mirabilis) 1
Common pitfall: Prescribing cephalexin for infections in areas with high MRSA prevalence without considering alternative agents or ensuring adequate source control through drainage procedures.
Practical Prescribing
For a typical adult with an uncomplicated wound infection:
- Mild infection: Cephalexin 500 mg twice daily × 7-10 days
- Moderate infection or uncertain severity: Cephalexin 500 mg four times daily × 7-10 days
- If MRSA suspected: Consider alternative agents (trimethoprim-sulfamethoxazole, doxycycline, or clindamycin based on local susceptibility patterns) 2
The medication can be taken without regard to meals, is rapidly absorbed, and achieves peak serum levels within 1 hour 1. The twice-daily regimen offers improved convenience and adherence for appropriate cases 5.