What is the recommended dosage of cephalexin (cephalexin) for pediatric patients?

Pediatric Dosing of Cephalexin

The standard pediatric dose of cephalexin is 25-50 mg/kg/day divided into 3-4 doses, with specific infection-based adjustments: 25-50 mg/kg/day in 4 divided doses for impetigo and uncomplicated skin infections, 75-100 mg/kg/day in 3-4 divided doses for MSSA skin and soft tissue infections, and 75-100 mg/kg/day in 4 divided doses for otitis media. 1, 2

Standard Dosing by Indication

Skin and Soft Tissue Infections

For impetigo and uncomplicated skin infections:

• 25-50 mg/kg/day divided into 4 doses (every 6 hours) 1, 3
• Alternative dosing: May divide total daily dose and administer every 12 hours for streptococcal pharyngitis and skin/skin structure infections in patients over 1 year of age 1

For MSSA skin and soft tissue infections (preferred oral agent):

• 75-100 mg/kg/day in 3-4 divided doses 2, 4
• This higher dose is specifically recommended by the Infectious Diseases Society of America for methicillin-susceptible Staphylococcus aureus infections 2

Otitis Media

• 75-100 mg/kg/day in 4 divided doses 1
• Clinical studies have demonstrated this higher dosing is required for adequate treatment of middle ear infections 1

Severe Infections

• Dosage may be doubled from the standard 25-50 mg/kg/day regimen 1
• For infections caused by less susceptible organisms, larger doses may be needed 1

Alternative Dosing Frequencies (Evidence-Based)

Three Times Daily Dosing

• 45 mg/kg/dose (maximum 1,500 mg/dose) three times daily is effective for bone and joint infections 5, 6
• This regimen achieved 99% cure rate (147/149 children) in a large retrospective audit 5
• Pharmacokinetic modeling supports 15-25 mg/kg three times daily for MSSA with MIC 1-2 mg/L, and 45 mg/kg three times daily for MIC 4 mg/L 7

Twice Daily Dosing

• 22-45 mg/kg/dose twice daily for MSSA with MIC 1-2 mg/L 7
• 80 mg/kg/dose twice daily for MSSA with MIC 4 mg/L 7
• Less frequent dosing improves adherence but requires higher individual doses to maintain pharmacodynamic targets 7

Important Clinical Considerations

Duration of Therapy

• Minimum 10 days for β-hemolytic streptococcal infections 1
• 7-14 days for uncomplicated cystitis in patients over 15 years 1
• Standard duration is typically 7 days for most infections, depending on clinical response 2

Special Populations

• Appropriate for penicillin-allergic patients except those with immediate hypersensitivity reactions 2, 3
• Children may require higher doses per kilogram than adults due to greater body water turnover 8
• Doses listed are not appropriate for neonates; refer to specialized neonatal dosing guidelines 2

Maximum Doses

• Daily doses should not exceed 4 grams 1
• If daily doses greater than 4 grams are required, parenteral cephalosporins should be considered 1
• Individual dose maximum is typically 750 mg for standard dosing, or 1,500 mg for high-dose three times daily regimens 5

Tolerability of Higher Doses

The higher dose regimen of 45 mg/kg three times daily is well tolerated:

• Only 4/149 children (2.7%) experienced gastrointestinal symptoms 5
• 13/149 children (8.7%) developed neutropenia, which was mild in most cases with no associated complications 5
• No dose reduction needed for mild adverse effects in most cases 5

Common Pitfalls to Avoid

• Do not use four times daily dosing when three times daily or twice daily regimens are appropriate - less frequent dosing improves adherence without compromising efficacy for many infections 7, 5
• Do not underdose MSSA infections - use the higher 75-100 mg/kg/day range rather than the standard 25-50 mg/kg/day 2, 4
• Do not forget to adjust for renal impairment - patients with creatinine clearance <30 mL/min require dose reduction proportional to reduced function 8
• Do not use cephalexin for MRSA infections - it is only effective against methicillin-susceptible organisms 2