Pediatric Dose of Keflex (Cephalexin)
Standard Dosing
The recommended pediatric dose of cephalexin is 25-50 mg/kg/day divided into doses given every 6-12 hours, with the specific dosing frequency and amount depending on the type and severity of infection. 1
General Dosing Guidelines
- For most infections: Administer 25-50 mg/kg/day in divided doses 1
- For streptococcal pharyngitis and skin/soft tissue infections: The total daily dose may be divided and given every 12 hours in children over 1 year of age 1
- For otitis media: Clinical studies demonstrate that 75-100 mg/kg/day in 4 divided doses is required 1
- For severe infections: The dosage may be doubled 1
Infection-Specific Dosing
For impetigo and uncomplicated skin infections: Use 25 mg/kg/day divided into 4 doses 2
For methicillin-susceptible Staphylococcus aureus (MSSA) skin and soft tissue infections: Administer 25 mg/kg/day in 4 divided doses (approximately 500 mg four times daily for adults, scaled to pediatric weight) 2
Practical Dosing Examples from FDA Label
For a 10 kg (22 lb) child using suspension 1:
- 125 mg/5 mL formulation: ½ to 1 teaspoon four times daily
- 250 mg/5 mL formulation: ¼ to ½ teaspoon four times daily
For a 20 kg (44 lb) child using suspension 1:
- 125 mg/5 mL formulation: 1 to 2 teaspoons four times daily
- 250 mg/5 mL formulation: ½ to 1 teaspoon four times daily
For a 40 kg (88 lb) child using suspension 1:
- 125 mg/5 mL formulation: 2 to 4 teaspoons four times daily
- 250 mg/5 mL formulation: 1 to 2 teaspoons four times daily
Alternative Dosing Frequencies
Recent evidence supports less frequent dosing regimens to improve adherence, though these are not yet FDA-approved standard dosing 3, 4:
- Three times daily: 45 mg/kg/dose (maximum 1.5 g) has demonstrated efficacy and tolerability for bone and joint infections, with 99% cure rate 3
- Twice daily: 22-45 mg/kg/dose for MSSA with MIC 1-2 mg/L based on pharmacokinetic modeling 4
Important Clinical Considerations
Duration of therapy: For β-hemolytic streptococcal infections, administer therapeutic dosage for at least 10 days 1
Storage: After mixing suspension, refrigerate and discard after 14 days 1
Penicillin allergy: Cephalexin is appropriate for penicillin-allergic patients except those with immediate hypersensitivity reactions 2
Higher doses may be needed in children due to greater body water turnover compared to adults 5