Is cefalexin (Ceflex) suitable for treating a skin infection in a 2-week-old infant?

Cefalexin (Ceflex) is NOT recommended for skin infections in a 2-week-old infant

Cefalexin should not be used in neonates (infants under 1 month of age) as the pediatric dosing guidelines specifically exclude this age group, and neonatal-specific antibiotics are required for this vulnerable population. 1, 2

Why Cefalexin is Contraindicated in Neonates

Age-Specific Exclusion

• The FDA label for cefalexin and clinical practice guidelines explicitly state that dosages listed are "not appropriate for neonates" 1, 2
• Pediatric dosing recommendations for cefalexin begin "beyond the neonatal period" 1
• A 2-week-old infant is still within the neonatal period (birth to 28 days of life), making cefalexin inappropriate 1

Pharmacokinetic Concerns

• Neonates have immature renal function and altered drug clearance compared to older infants and children 3
• Children generally require higher doses per kilogram than adults due to greater body water turnover, but neonates require specialized dosing that has not been established for cefalexin 3
• The drug's distribution and elimination characteristics in neonates differ significantly from older populations 3

Appropriate Alternatives for Neonatal Skin Infections

First-Line Options

• For suspected staphylococcal/streptococcal infections: Nafcillin or oxacillin at 50 mg/kg/dose every 6 hours IV 1
• Alternative: Cefazolin at 33 mg/kg/dose every 8 hours IV (though still requires careful consideration in neonates) 1
• For penicillin-susceptible organisms: Penicillin G at 100,000-150,000 units/kg/day IV in divided doses every 4-6 hours 1

Critical Management Principles

• Neonates with skin infections require immediate medical evaluation and often hospitalization, as they are at high risk for rapid progression to systemic infection and sepsis 1
• Bacterial cultures should be obtained before initiating antibiotics to guide definitive therapy 1
• Empiric broad-spectrum coverage may be needed initially, with de-escalation based on culture results 1

Special Neonatal Considerations

Risk of Rapid Deterioration

• Neonates, particularly those under 2 weeks old, can deteriorate rapidly from localized skin infections to sepsis 1
• Close monitoring for fever, lethargy, poor feeding, and signs of systemic illness is essential 1

Infection Prevention

• Regular bacterial swabs (twice weekly) from affected areas, flexures, and any invasive line sites should be performed 1
• Prophylactic antibiotics are generally not recommended but may be considered in high-risk situations 1

Bottom line: A 2-week-old infant with a skin infection requires immediate pediatric or neonatal evaluation, appropriate cultures, and neonatal-specific antibiotic therapy—not cefalexin. 1, 2