Cephalexin Dosing for Cellulitis in a 1-Year-Old
For a 1-year-old toddler with cellulitis, administer cephalexin 25-50 mg/kg/day divided into 3-4 doses (or 12.5-25 mg/kg/dose every 6-8 hours), with a maximum single dose of 500 mg. 1
Standard Dosing Regimen
The FDA-approved dosing for pediatric patients is 25-50 mg/kg/day in divided doses 1. For a 1-year-old with cellulitis:
- Standard approach: 25-50 mg/kg/day divided every 6 hours (four times daily) 1
- Alternative approach: 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 1
Practical Dosing Examples
For skin and soft tissue infections caused by methicillin-susceptible Staphylococcus aureus (MSSA), the IDSA guidelines recommend oral cephalexin at 25-50 mg/kg/day in 4 divided doses for children 2. This translates to approximately:
- 10 kg child: 62.5-125 mg every 6 hours (using 125 mg/5 mL suspension: ½ to 1 teaspoon four times daily) 1
- For severe infections, the dosage may be doubled 1
Dosing Frequency Considerations
While four times daily dosing is the FDA-approved standard 1, recent evidence suggests less frequent dosing may be acceptable:
- Three times daily: High-dose cephalexin 45 mg/kg/dose (maximum 1.5 g) three times daily has shown efficacy and tolerability in children with bone and joint infections 3
- Twice daily: For MSSA with MIC ≤2 mg/L, doses of 22-45 mg/kg twice daily may achieve adequate pharmacodynamic targets 4
However, for a 1-year-old with cellulitis, stick with the FDA-approved four times daily regimen (or twice daily if using the alternative dosing for skin infections) to ensure adequate coverage 1.
Important Clinical Considerations
Duration: Continue treatment for at least 7-10 days, or until clinical resolution is achieved 2. The suspension remains stable for 14 days when refrigerated after mixing 1.
Pathogen coverage: Cephalexin provides excellent coverage for MSSA and Group A Streptococcus, the most common pathogens in pediatric cellulitis 2. If MRSA is suspected (failed initial therapy, severe infection with systemic signs, or known MRSA colonization), alternative antibiotics such as clindamycin should be considered 2.
Monitoring: Reassess at 48-72 hours to ensure clinical improvement (decreased erythema, swelling, warmth, and tenderness) 2.