Cefalexin Prophylaxis for Minor Cuts
For a minor cut requiring antibiotic prophylaxis, cefalexin 500 mg orally three to four times daily for 7 days is the recommended regimen, though prophylactic antibiotics are generally not indicated for simple, clean minor cuts unless there are specific risk factors for infection. 1, 2
When Prophylaxis Is Actually Indicated
Most minor cuts do not require antibiotic prophylaxis. Consider prophylaxis only when specific risk factors are present:
- Contaminated wounds (soil, feces, saliva exposure) 3
- Deep puncture wounds or wounds with devitalized tissue 4
- Immunocompromised patients (diabetes, immunosuppression) 2
- Wounds in high-risk locations (hands, feet, joints) 4
- Delayed presentation (>6-8 hours after injury) 3
For simple, clean minor cuts without these risk factors, topical antimicrobial agents are sufficient. 2
Recommended Dosing Regimen
Adults
- Standard dose: 500 mg orally three times daily for 7 days 2
- For more severe or high-risk wounds: 500 mg orally four times daily (every 6 hours) 1, 4
- The FDA-approved dosing range is 1-4 grams daily in divided doses 5
Pediatric Patients
- Standard dose: 25-50 mg/kg/day divided into 4 doses 1, 5
- For higher-risk infections: 75-100 mg/kg/day divided into 3-4 doses 4
Duration of Therapy
- Typical duration: 7 days for uncomplicated skin infections 2
- Extend treatment if no improvement within 5 days 2
- Minimum 10 days if streptococcal infection is confirmed (to prevent rheumatic fever) 1
Critical Microbiological Considerations and Pitfalls
What Cefalexin Covers Well
- Methicillin-susceptible Staphylococcus aureus (MSSA) - excellent coverage 4, 2
- Streptococcus species - excellent coverage 4, 2
What Cefalexin Does NOT Cover (Common Pitfalls)
- MRSA - completely ineffective; use trimethoprim-sulfamethoxazole, doxycycline, or clindamycin instead 1, 4, 2
- Pasteurella multocida - inadequate for animal bites; consider amoxicillin-clavulanate 1, 4
- Eikenella corrodens - inadequate for human bites 1
- Anaerobes - limited coverage; unsuitable for deep abscesses 1, 4
- Pseudomonas aeruginosa - no activity 1
When to Avoid Cefalexin
- History of immediate hypersensitivity to penicillin (anaphylaxis, angioedema, urticaria) - avoid due to cross-reactivity 1, 2
- Non-immediate penicillin reactions - cefalexin remains appropriate 4
Alternative Approach: Pre-Procedure Single Dose
If prophylaxis is given immediately before wound repair (similar to surgical prophylaxis):
- Adults: 1000 mg orally as a single dose before wound repair, followed by 250 mg every 6 hours for 5 days 3
- This approach showed 9.6% infection rate in clinical trials 3
Monitoring and Follow-Up
- Reassess at 5 days - if no improvement, extend therapy or broaden coverage 2
- Watch for systemic signs (fever, spreading erythema, lymphangitis) - may require parenteral antibiotics or broader coverage 2
- If MRSA suspected based on local epidemiology or purulent drainage - switch to MRSA-active agent immediately 4, 2