Cephalexin Dosing for Pediatric Patients
The recommended dosage of cephalexin (Keflex) for pediatric patients is 25 to 50 mg/kg/day divided into 2-4 doses, with specific dosing depending on the type and severity of infection. 1
Standard Dosing Recommendations
- For most pediatric infections, the standard dosage is 25-50 mg/kg/day divided into 2-4 doses 1
- For streptococcal pharyngitis in children over 1 year of age and for skin/skin structure infections, the total daily dose may be administered every 12 hours (twice daily) 1
- For severe infections, the dosage may be doubled 1
- For otitis media, a higher dosage of 75-100 mg/kg/day in 4 divided doses is required 1
Dosing Based on Weight and Formulation
For cephalexin suspension, the FDA recommends the following dosing:
Four times daily (q.i.d.) dosing:
- 10 kg (22 lb): 1/2 to 1 tsp of 125 mg/5 mL or 1/4 to 1/2 tsp of 250 mg/5 mL 1
- 20 kg (44 lb): 1 to 2 tsp of 125 mg/5 mL or 1/2 to 1 tsp of 250 mg/5 mL 1
- 40 kg (88 lb): 2 to 4 tsp of 125 mg/5 mL or 1 to 2 tsp of 250 mg/5 mL 1
Twice daily (b.i.d.) dosing:
- 10 kg (22 lb): 1 to 2 tsp of 125 mg/5 mL or 1/2 to 1 tsp of 250 mg/5 mL 1
- 20 kg (44 lb): 2 to 4 tsp of 125 mg/5 mL or 1 to 2 tsp of 250 mg/5 mL 1
- 40 kg (88 lb): 4 to 8 tsp of 125 mg/5 mL or 2 to 4 tsp of 250 mg/5 mL 1
Infection-Specific Dosing
MSSA infections: Cephalexin is the preferred oral agent for methicillin-susceptible Staphylococcus aureus infections 2
- For MSSA skin and soft tissue infections: 75-100 mg/kg/day in 3-4 divided doses 3
- Recent research suggests that for MSSA infections, twice-daily dosing requires 22-45 mg/kg/dose for MICs of 1-2 mg/L and 80 mg/kg/dose for MIC of 4 mg/L 4
- For thrice-daily dosing, 15-25 mg/kg/dose is required for MICs of 1-2 mg/L and 45 mg/kg/dose for MIC of 4 mg/L 4
Streptococcal pharyngitis: Treatment should continue for at least 10 days 1
Musculoskeletal infections: Recent research supports cephalexin 25 mg/kg/dose (maximum 750 mg/dose) three times daily for MSSA with MICs ≤ 4 mg/L 5
Important Clinical Considerations
- Cephalexin is rapidly absorbed in the upper intestine and not in the stomach 6
- Children may require higher doses per kilogram than adults due to their greater body water turnover 6
- For improved adherence, twice-daily or thrice-daily regimens may be considered for certain infections, though traditional recommendations have been for four-times-daily dosing 4, 5
- Cephalexin suspension should be stored in the refrigerator after mixing and may be kept for 14 days without significant loss of potency 1
Cautions and Monitoring
- No dosage adjustment is needed for mild to moderate renal impairment, but dosage reduction is required for patients with creatinine clearance less than 30 ml/min 6
- Monitor for signs of allergic reactions, especially in patients with known penicillin allergy (though cross-reactivity is generally low) 6