Cephalexin Dosage for Impetigo in a 3-Year-Old Child
The appropriate dosage of cephalexin for a 3-year-old child with impetigo is 25-50 mg/kg/day divided into 2-4 doses per day for 10 days. 1
Dosing Recommendations
For a typical 3-year-old child (approximately 15-20 kg):
- Dosage range: 375-1000 mg total daily dose
- Frequency options:
- 4 times daily (q6h): 94-250 mg per dose
- 3 times daily (q8h): 125-333 mg per dose
- 2 times daily (q12h): 188-500 mg per dose
The FDA-approved cephalexin label specifically provides these pediatric dosing guidelines:
- Standard dosage: 25-50 mg/kg/day divided into 4 doses
- For skin and skin structure infections: The total daily dose may be divided and administered every 12 hours 1
Administration Considerations
- Cephalexin suspension is available in two concentrations:
- 125 mg/5 mL
- 250 mg/5 mL
- For a 15-20 kg child using the 125 mg/5 mL suspension:
- If dosing twice daily: 2-4 teaspoons per dose
- If dosing four times daily: 1-2 teaspoons per dose 1
- The suspension should be refrigerated after mixing and remains stable for 14 days 1
Treatment Duration
Treatment should be continued for 10 days to ensure complete eradication of the causative organism 2. This duration is particularly important for streptococcal infections to prevent complications.
Efficacy for Impetigo
Cephalexin is highly effective for impetigo, which is typically caused by Staphylococcus aureus or Streptococcus pyogenes. Studies have shown that cephalexin is superior to penicillin for impetigo treatment, with no treatment failures observed in comparative studies 3.
Alternative Treatments
If cephalexin cannot be used (e.g., in cases of severe penicillin allergy with anaphylaxis):
- Clindamycin: 7 mg/kg/dose three times daily (max = 300 mg/dose) for 10 days 2
- For MRSA concerns: Consider clindamycin or trimethoprim/sulfamethoxazole 4
Important Considerations
- Avoid cephalexin in patients with immediate-type hypersensitivity to penicillin due to potential cross-reactivity (up to 10% of cases) 5
- Topical antibiotics like mupirocin or retapamulin may be considered for very limited disease, but oral therapy is often preferred for children with multiple lesions 4, 6
- Reassess the child within 48-72 hours to evaluate treatment response 5
- Complete the full 10-day course even if symptoms improve quickly to prevent recurrence and complications
Monitoring
- Watch for common side effects: gastrointestinal upset, diarrhea, or rash
- Discontinue medication and seek medical attention if severe allergic reactions occur
- Ensure adequate hydration during treatment
By following these dosing guidelines, cephalexin provides effective coverage against the common bacterial pathogens causing impetigo in children while maintaining an excellent safety profile.