Cephalexin Pediatric Dosing
For pediatric patients, cephalexin should be dosed at 25-50 mg/kg/day divided into doses, with the specific regimen depending on infection severity and type.
Standard Dosing Recommendations
According to the FDA label, the usual recommended daily dosage for pediatric patients is 25-50 mg/kg/day in divided doses 1. This can be administered in several ways:
Dosing Frequency Options
For most infections (including skin/soft tissue and streptococcal pharyngitis):
- Every 6 hours (QID): 25-50 mg/kg/day divided into 4 doses
- Every 12 hours (BID): For patients >1 year with pharyngitis or skin infections, the total daily dose may be divided and given twice daily 1
Weight-based dosing examples (using 125 mg/5 mL or 250 mg/5 mL suspension):
- 10 kg (22 lb): 2.5-5 mL QID (125 mg/5 mL) or 1.25-2.5 mL QID (250 mg/5 mL)
- 20 kg (44 lb): 5-10 mL QID (125 mg/5 mL) or 2.5-5 mL QID (250 mg/5 mL)
- 40 kg (88 lb): 10-20 mL QID (125 mg/5 mL) or 5-10 mL QID (250 mg/5 mL) 1
Infection-Specific Dosing
Otitis Media
75-100 mg/kg/day in 4 divided doses is required based on clinical studies 1. This is the higher end of the dosing spectrum and should not be reduced.
Severe Infections
Double the standard dose may be used for severe infections 1.
Methicillin-Susceptible Staphylococcus aureus (MSSA)
For oral step-down therapy in pneumonia or bone/joint infections: 75-100 mg/kg/day in 3 or 4 doses 2, 3, 2, 3.
Alternative Dosing Regimens (Based on Recent Evidence)
Recent pharmacokinetic studies support less frequent dosing to improve adherence:
Three Times Daily (TID) Dosing
45 mg/kg/dose (maximum 1.5 g) three times daily has been shown effective and well-tolerated for bone and joint infections, with 99% cure rates 4. This regimen achieves the same pharmacodynamic targets as traditional QID dosing 5.
Twice Daily (BID) Dosing
For MSSA with MIC ≤2 mg/L: 22-45 mg/kg/dose twice daily achieves adequate pharmacodynamic targets 5. Clinical outcomes for osteoarticular infections were similar between BID and QID dosing 6.
Treatment Duration
- Streptococcal infections: Minimum 10 days 1
- Cystitis: 7-14 days 1
- Most other infections: 7-10 days typical
Important Caveats
Maximum daily dose: If >4 g/day is required, consider parenteral cephalosporins 1.
Neutropenia monitoring: While rare, mild neutropenia can occur with higher doses (seen in 13/149 patients in one study), though typically without complications 4.
Suspension stability: After reconstitution, refrigerate and use within 14 days 1.
Weight considerations: Patients weighing over the weight corresponding to dosing maximums are at highest risk for dosing errors—avoid overdosing by capping individual doses appropriately 7.