Cephalexin Pediatric Dose
The recommended pediatric dosage of cephalexin is 25-50 mg/kg/day divided into 3-4 doses, with higher doses (75-100 mg/kg/day in 4 divided doses) required for otitis media. 1
Standard Dosing by Indication
General Infections (Skin, Soft Tissue, Pharyngitis)
- Standard dose: 25-50 mg/kg/day divided every 6 hours (QID) or every 12 hours (BID) 1
- For streptococcal pharyngitis and skin/soft tissue infections in children >1 year, the total daily dose may be divided and given every 12 hours 1
Otitis Media
- Higher dose required: 75-100 mg/kg/day in 4 divided doses 1, 2
- This higher dosing is specifically validated in clinical studies for adequate middle ear penetration 2
Severe Infections
- Double the standard dose when treating severe infections 1
Context-Specific Dosing from Guidelines
Methicillin-Susceptible Staphylococcus aureus (MSSA)
For oral step-down therapy or mild MSSA infections (including pneumonia):
- 75-100 mg/kg/day divided into 3 or 4 doses 3, 4, 3, 4
- This is the preferred oral agent for MSSA in pediatric patients 5
Alternative Dosing Frequencies
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 achieves appropriate pharmacodynamic targets 6, 7
- This regimen showed 99% cure rate in bone and joint infections with good tolerability 6
- For MSSA with MIC ≤2 mg/L: 15-25 mg/kg TID; for MIC 4 mg/L: 45 mg/kg TID 7
Twice Daily (BID) Dosing
- For MSSA with MIC 1-2 mg/L: 22-45 mg/kg BID 7
- For MSSA with MIC 4 mg/L: 80 mg/kg BID 7
- Note: BID dosing requires higher per-dose amounts and may not be optimal for all infections
Practical Dosing Table (from FDA Label)
| Weight | 125 mg/5 mL QID | 250 mg/5 mL QID |
|---|---|---|
| 10 kg (22 lb) | ½-1 tsp | ¼-½ tsp |
| 20 kg (44 lb) | 1-2 tsp | ½-1 tsp |
| 40 kg (88 lb) | 2-4 tsp | 1-2 tsp |
Important Caveats
- Duration for streptococcal infections: Administer for at least 10 days to prevent rheumatic fever 1
- Suspension stability: After reconstitution, refrigerate and use within 14 days 1
- Maximum daily dose: If >4 g/day is required, consider parenteral cephalosporins 1
- Tolerability: Higher doses (45 mg/kg TID) are generally well-tolerated, though mild neutropenia and GI symptoms can occur 6
Clinical Decision Algorithm
Identify the infection type:
- Otitis media → 75-100 mg/kg/day divided QID
- MSSA skin/soft tissue or bone/joint → 75-100 mg/kg/day divided TID or QID
- Streptococcal pharyngitis → 25-50 mg/kg/day divided BID or QID
- Uncomplicated UTI → 25-50 mg/kg/day divided QID
Consider adherence factors:
- If adherence is a concern, use 45 mg/kg TID dosing (max 1.5 g/dose) for MSSA infections 6
- Standard QID dosing remains appropriate when adherence is not an issue
Adjust for severity:
- Severe infections → double the standard dose 1
- Life-threatening infections → consider parenteral therapy instead