What is the recommended dose of cephalexin (cephalexin) for children?

Cephalexin Dosing in Children

For most pediatric infections, cephalexin should be dosed at 25-50 mg/kg/day divided into 2-4 doses, but for methicillin-susceptible Staphylococcus aureus (MSSA) skin and soft tissue infections, use the higher dose of 75-100 mg/kg/day divided into 3-4 doses. 1, 2

Standard Dosing by Indication

Mild to Moderate Infections

• The FDA-approved standard pediatric dose is 25-50 mg/kg/day in divided doses for most common infections including streptococcal pharyngitis and uncomplicated skin infections 3
• For streptococcal pharyngitis and skin/soft tissue infections in children over 1 year, the total daily dose may be divided and given every 12 hours (twice daily) 3

MSSA Skin and Soft Tissue Infections

• The Infectious Diseases Society of America recommends 75-100 mg/kg/day divided into 3-4 doses for MSSA infections, which is substantially higher than standard dosing 4, 1, 2
• This higher dosing range is critical—avoid the common pitfall of underdosing MSSA infections by using the standard 25-50 mg/kg/day range instead of the recommended 75-100 mg/kg/day 1

Otitis Media

• For otitis media specifically, 75-100 mg/kg/day in 4 divided doses is required based on clinical studies 3

Severe Infections

• In severe infections, the dosage may be doubled from the standard range 3

Practical Dosing Schedules

Four Times Daily (QID) Dosing

• This is the traditional FDA-approved regimen but can be challenging for adherence 3, 5
• Appropriate for standard infections at 25-50 mg/kg/day divided every 6 hours 3

Three Times Daily (TID) Dosing

• Recent evidence supports 45 mg/kg/dose (maximum 1.5 g) three times daily as an effective alternative with better adherence 6
• This regimen achieved 99% cure rates in children with bone and joint infections 6
• For MSSA with MIC 1-2 mg/L, 15-25 mg/kg TID is adequate; for MIC 4 mg/L, 45 mg/kg TID is required 5

Twice Daily (BID) Dosing

• For streptococcal pharyngitis and uncomplicated skin infections, twice-daily dosing is FDA-approved 3
• For MSSA with MIC 1-2 mg/L, 22-45 mg/kg BID achieves pharmacodynamic targets; for MIC 4 mg/L, 80 mg/kg BID is needed 5

Important Clinical Considerations

Duration of Therapy

• Standard duration is typically 7 days for most infections, adjusted based on clinical response 1
• For β-hemolytic streptococcal infections, treat for at least 10 days 3
• Cystitis therapy should continue for 7-14 days 3

Allergy Considerations

• Cephalexin is appropriate for penicillin-allergic patients except those with immediate hypersensitivity reactions 7, 1

Age Restrictions

• Do not use standard pediatric doses in neonates—refer to specialized neonatal dosing guidelines 1
• Dosing recommendations apply to children over 1 year of age for most indications 3

Critical Pitfalls to Avoid

Spectrum Limitations

• Never use cephalexin for MRSA infections—it is only effective against methicillin-susceptible organisms 1
• Cephalexin is not appropriate for pneumococcal pneumonia as first-line therapy; the guideline evidence focuses on its role for MSSA infections 4

Dosing Errors

• The most common error is underdosing MSSA infections by using 25-50 mg/kg/day instead of the required 75-100 mg/kg/day 1
• Children may require higher doses per kilogram than adults due to greater body water turnover 8

Tolerability

• The higher doses (45 mg/kg TID) are generally well tolerated, with only 4/149 children experiencing gastrointestinal symptoms and 13 developing mild neutropenia without complications in one large study 6