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

Pediatric Dosage of Cephalexin

The recommended pediatric dosage of cephalexin is 25-50 mg/kg/day divided into doses, with the specific frequency and amount depending on the type and severity of infection. 1

Standard Dosing by Indication

Uncomplicated Skin Infections and Impetigo

• 25 mg/kg/day divided into 4 doses is recommended for impetigo and uncomplicated skin infections 2
• This translates to approximately 6.25 mg/kg per dose given every 6 hours 2

MSSA Skin and Soft Tissue Infections

• 25 mg/kg/day in 4 divided doses for methicillin-susceptible Staphylococcus aureus infections 2
• Cephalexin is the preferred oral agent for MSSA infections according to major guidelines 3

Streptococcal Pharyngitis and Mild-Moderate Infections

• The total daily dose may be divided and administered every 12 hours (twice daily) for streptococcal pharyngitis in patients over 1 year of age 1
• For β-hemolytic streptococcal infections, continue therapy for at least 10 days 1

Severe Infections

• Dosage may be doubled for severe infections 1
• For infections caused by less susceptible organisms, larger doses up to 50 mg/kg/day may be needed 1

Otitis Media

• Requires 75-100 mg/kg/day in 4 divided doses based on clinical studies 1
• This higher dose is necessary to achieve adequate middle ear fluid concentrations 1

Practical Dosing Tables

For standard infections (25-50 mg/kg/day): 1

Four Times Daily Dosing:

• 10 kg child: 125-250 mg per dose (½ to 1 tsp of 125 mg/5 mL suspension)
• 20 kg child: 250-500 mg per dose (1 to 2 tsp of 125 mg/5 mL suspension)
• 40 kg child: 500-1000 mg per dose (2 to 4 tsp of 125 mg/5 mL suspension)

Twice Daily Dosing (for pharyngitis/mild infections):

• 10 kg child: 125-250 mg per dose
• 20 kg child: 250-500 mg per dose
• 40 kg child: 500-1000 mg per dose

Important Clinical Considerations

Dosing Frequency Options

• While four times daily dosing is FDA-approved, emerging evidence supports less frequent dosing regimens to improve adherence 1, 4
• Recent pharmacokinetic modeling suggests 22-45 mg/kg twice daily may achieve adequate targets for MSSA with MIC ≤2 mg/L 4
• Three times daily dosing at 45 mg/kg/dose (maximum 1.5 g) has demonstrated 99% cure rates in bone and joint infections 5

Maximum Doses

• Daily doses should not exceed 4 grams per day 1
• If doses greater than 4 g daily are required, consider parenteral cephalosporins 1

Special Populations

• Penicillin-allergic patients: Cephalexin is appropriate except in those with immediate hypersensitivity reactions 2
• Renal impairment: Dosage reduction required when creatinine clearance is less than 30 mL/min 6

Administration and Storage

• Suspension should be refrigerated after mixing and may be kept for 14 days 1
• The drug is absorbed in the upper intestine, not the stomach 6
• Children may require higher doses per kilogram than adults due to greater body water turnover 6

Common Pitfalls to Avoid

• Inadequate dosing for otitis media: Remember to use the higher dose range (75-100 mg/kg/day) rather than standard dosing 1
• Premature discontinuation of streptococcal treatment: Must complete at least 10 days for β-hemolytic streptococcal infections to prevent rheumatic fever 1
• Using cephalexin for MRSA: This drug only covers methicillin-susceptible organisms; verify susceptibility before use 2, 3
• Forgetting to adjust for renal function: Cephalexin is renally cleared and requires dose adjustment in significant renal impairment 6