What is the recommended dosing of Keflex (cephalexin) for an infected ingrown toenail?

Cephalexin Dosing for Infected Ingrown Toenail

For an infected ingrown toenail, cephalexin should be dosed at 500 mg orally every 12 hours for 7-14 days in adults. 1

Dosing Guidelines

Adults:

• Standard dose: 500 mg orally every 12 hours
• Duration: 7-14 days (similar to uncomplicated skin infections)
• For severe infections: May increase to 500 mg every 6 hours
• Maximum daily dose: 4g per day

Pediatric Patients:

• Standard dose: 25-50 mg/kg/day divided into 2-4 doses
• For skin infections: Can be divided and administered every 12 hours
• For severe infections: Dosage may be doubled
• Weight-based dosing:
  • 10 kg: 125-250 mg every 12 hours
  • 20 kg: 250-500 mg every 12 hours
  • 40 kg: 500-1000 mg every 12 hours

Treatment Approach for Ingrown Toenails

Assessment of Infection Severity

• Mild: Local inflammation, minimal pain
• Moderate: Purulent drainage, increased pain, localized swelling
• Severe: Extensive cellulitis, significant pain, systemic symptoms

Management Algorithm

1. Local measures (for all severity levels):

   • Warm soaks with Epsom salt or dilute povidone-iodine solution
   • Proper nail trimming technique (straight across)
   • Cotton packing under ingrown nail edge if possible
   • Avoid tight footwear

2. Antibiotic therapy (for infected cases):

   • Initiate cephalexin at recommended doses
   • Consider culture if recurrent or treatment-resistant infection

3. Surgical intervention considerations:

   • Partial nail avulsion for recurrent cases
   • Chemical matrixectomy for definitive treatment

Important Clinical Considerations

Antibiotic Selection Rationale

Cephalexin is appropriate for infected ingrown toenails because:

• Effective coverage against common skin pathogens (Staphylococcus and Streptococcus species)
• Good tissue penetration
• Established safety profile
• Convenient dosing schedule

Evidence on Antibiotic Necessity

Research suggests that in cases where a chemical matrixectomy is performed, antibiotics may not significantly improve healing time 2. However, for cases with active infection without definitive surgical management, antibiotic therapy remains appropriate.

Monitoring and Follow-up

• Assess response within 48-72 hours
• Complete the full antibiotic course even if symptoms improve
• Consider surgical referral if no improvement after 3-5 days of therapy

Common Pitfalls to Avoid

1. Underdosing: Using inadequate doses may lead to treatment failure and potential resistance
2. Inadequate duration: Stopping antibiotics too early can result in recurrence
3. Neglecting local measures: Antibiotics alone without addressing the underlying mechanical issue
4. Missing fungal co-infection: Consider concomitant onychomycosis that may require antifungal therapy
5. Failing to recognize severe infection: Cellulitis extending beyond the toe may require more aggressive therapy or parenteral antibiotics

Remember that proper nail care and addressing the mechanical factors causing the ingrown nail are essential components of treatment alongside appropriate antibiotic therapy.