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

Cephalexin Pediatric Dosing

Standard Dosing Recommendation

The recommended pediatric dose of cephalexin is 25-50 mg/kg/day divided into doses given every 6-12 hours, depending on infection severity and type. 1

Dosing by Infection Type

Uncomplicated Skin Infections and Impetigo

• 25 mg/kg/day divided into 4 doses (every 6 hours) for impetigo and uncomplicated skin infections 2
• This represents the lower end of the dosing spectrum and is appropriate for mild infections 1

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 the Infectious Diseases Society of America and American Academy of Pediatrics 3

Streptococcal Pharyngitis and Mild Skin 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 and for skin and skin structure infections 1
• This simplified dosing improves adherence while maintaining efficacy 1

Severe Infections

• In severe infections, the dosage may be doubled to 50-100 mg/kg/day 1
• For otitis media specifically, 75-100 mg/kg/day in 4 divided doses is required 1

Weight-Based Dosing Tables

Four Times Daily Dosing (Q.I.D.)

Using 125 mg/5 mL suspension: 1

• 10 kg (22 lb): 1/2 to 1 teaspoon every 6 hours
• 20 kg (44 lb): 1 to 2 teaspoons every 6 hours
• 40 kg (88 lb): 2 to 4 teaspoons every 6 hours

Using 250 mg/5 mL suspension: 1

• 10 kg (22 lb): 1/4 to 1/2 teaspoon every 6 hours
• 20 kg (44 lb): 1/2 to 1 teaspoon every 6 hours
• 40 kg (88 lb): 1 to 2 teaspoons every 6 hours

Twice Daily Dosing (B.I.D.)

Using 125 mg/5 mL suspension: 1

• 10 kg (22 lb): 1 to 2 teaspoons twice daily
• 20 kg (44 lb): 2 to 4 teaspoons twice daily
• 40 kg (88 lb): 4 to 8 teaspoons twice daily

Using 250 mg/5 mL suspension: 1

• 10 kg (22 lb): 1/2 to 1 teaspoon twice daily
• 20 kg (44 lb): 1 to 2 teaspoons twice daily
• 40 kg (88 lb): 2 to 4 teaspoons twice daily

Special Considerations

Duration of Therapy

• For β-hemolytic streptococcal infections, administer for at least 10 days to prevent rheumatic fever 1
• For cystitis, continue therapy for 7-14 days 1

Penicillin Allergy

• Cephalexin is appropriate for penicillin-allergic patients except those with immediate hypersensitivity reactions (anaphylaxis, urticaria) 2
• This is a critical safety consideration when selecting cephalexin as an alternative 2

Maximum Daily Dose

• If daily doses greater than 4 g are required, parenteral cephalosporins should be considered 1
• This typically applies to older adolescents approaching adult weight 1

Emerging Evidence on Reduced Frequency Dosing

Recent pharmacokinetic studies suggest alternative dosing regimens may be effective: 4, 5, 6

• 45 mg/kg/dose (maximum 1.5 g) three times daily has shown 99% cure rates in bone and joint infections with good tolerability 4
• 25 mg/kg/dose three times daily achieves pharmacodynamic targets for MSSA with MIC ≤2 mg/L 5
• These regimens improve adherence but are not yet FDA-approved standard dosing 4, 5

Common Pitfalls to Avoid

• Do not underdose severe infections: The standard 25 mg/kg/day may be insufficient for serious infections requiring 50-100 mg/kg/day 1
• Do not use in immediate penicillin hypersensitivity: Cross-reactivity can occur in patients with anaphylactic reactions to penicillins 2
• Ensure adequate duration for streptococcal infections: Premature discontinuation before 10 days increases risk of rheumatic fever 1
• Refrigerate suspension after mixing: The reconstituted suspension maintains potency for only 14 days when refrigerated 1