Pediatric Dosing of Cephalexin
The recommended daily dosage of cephalexin for pediatric patients is 25 to 50 mg/kg divided into 4 doses (every 6 hours) or 2 doses (every 12 hours), depending on the infection being treated. 1
Standard Dosing Guidelines
- For most infections, cephalexin should be dosed at 25-50 mg/kg/day divided into 4 doses (every 6 hours) or 2 doses (every 12 hours) 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
- In 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
Weight-Based Dosing Chart
For cephalexin suspension:
| Weight | 125 mg/5 mL (4 times daily) | 250 mg/5 mL (4 times daily) |
|---|---|---|
| 10 kg | 1/2 to 1 tsp | 1/4 to 1/2 tsp |
| 20 kg | 1 to 2 tsp | 1/2 to 1 tsp |
| 40 kg | 2 to 4 tsp | 1 to 2 tsp |
For twice-daily dosing:
| Weight | 125 mg/5 mL (twice daily) | 250 mg/5 mL (twice daily) |
|---|---|---|
| 10 kg | 1 to 2 tsp | 1/2 to 1 tsp |
| 20 kg | 2 to 4 tsp | 1 to 2 tsp |
| 40 kg | 4 to 8 tsp | 2 to 4 tsp |
| [1] |
Special Clinical Scenarios
- For treatment of methicillin-susceptible Staphylococcus aureus (MSSA) infections, cephalexin is the preferred oral agent 2
- For β-hemolytic streptococcal infections, cephalexin should be administered for at least 10 days 1
- Recent research suggests that for bone and joint infections, a higher dose of 45 mg/kg (maximum 1.5 g) three times daily may be effective and well-tolerated 3
Alternative Dosing Regimens
Recent pharmacokinetic studies have explored less frequent dosing to improve adherence:
- For twice-daily (BID) dosing targeting MSSA infections, doses of 22-45 mg/kg are required for MSSA with minimum inhibitory concentrations (MICs) of 1-2 mg/L 4
- For thrice-daily (TID) dosing, 15-25 mg/kg may be sufficient for the same MIC range 4
- Higher doses are needed for organisms with higher MICs 4
Important Considerations
- Cephalexin should be administered orally and is rapidly absorbed in the upper intestine 5
- Children may require higher doses per kilogram than adults due to their greater body water turnover 5
- After mixing the suspension, store in refrigerator; it may be kept for 14 days without significant loss of potency 1
- Cephalexin has demonstrated superior efficacy compared to penicillin in the treatment of group A beta-hemolytic streptococcal throat infections in children, with lower clinical and bacteriological failure rates 6
Monitoring and Adverse Effects
- Most children tolerate cephalexin well, but gastrointestinal symptoms may occur 3
- Neutropenia has been reported with high-dose regimens but is typically mild with no associated complications 3
- Cephalexin causes a very low incidence of allergy due to its stability and chemical configuration 5
Remember that these dosing recommendations are based on FDA-approved labeling and clinical guidelines, and should be adjusted based on the specific infection being treated and the patient's clinical response.