Cephalexin Use in 3-Year-Old Children
Cephalexin is acceptable for use in 3-year-old children, with appropriate dosing based on weight and indication. 1 The FDA has established safety and effectiveness of cephalexin in pediatric patients for the dosages described in approved prescribing information.
Appropriate Dosing for Children
- For most pediatric infections, cephalexin dosing ranges from 20-100 mg/kg/day divided into multiple doses 2, 3
- More recent evidence supports specific dosing regimens:
- For twice-daily dosing: 22-45 mg/kg per dose (for organisms with MIC 1-2 mg/L) 4
- For three-times-daily dosing: 15-25 mg/kg per dose (for organisms with MIC 1-2 mg/L) 4
- Higher doses of 45 mg/kg three times daily (maximum 1.5g) have been shown effective and well-tolerated for bone and joint infections 5
Indications in Children
Cephalexin is appropriate for treating:
- Upper respiratory tract infections (except those caused by Haemophilus influenzae, where failure rates approach 50%) 2
- Skin and soft tissue infections, particularly those caused by methicillin-susceptible Staphylococcus aureus (MSSA) 4, 3
- Urinary tract infections 3
- As oral continuation therapy for bone and joint infections 5
Important Considerations
- Complete the full course of therapy - Skipping doses or not completing the full course may decrease effectiveness and increase the likelihood of bacterial resistance 1
- Monitor for adverse effects - Most common are gastrointestinal upset, rash, and urticaria, though these are relatively infrequent 2
- Watch for diarrhea - Antibiotic-associated diarrhea, including potential C. difficile infection, can occur even up to two months after completing treatment 1
- Neutropenia risk - Higher doses may occasionally cause neutropenia, though it's typically mild without associated complications 5
Pharmacokinetic Considerations
- Cephalexin is not absorbed from the stomach but is totally and rapidly absorbed in the upper intestine 3
- Children may require higher doses per kilogram than adults due to greater body water turnover 3
- Cephalexin is primarily excreted unchanged through the kidneys, with 70-100% of the dose found in urine 6-8 hours after administration 3
Common Pitfalls to Avoid
- Inappropriate use for H. influenzae infections - Cephalexin has poor activity against H. influenzae, with approximately 50% failure rate 2, 6
- Inadequate dosing - Ensure weight-appropriate dosing to achieve therapeutic levels 4
- Premature discontinuation - Emphasize to caregivers the importance of completing the full prescribed course 1
- Using for viral infections - Cephalexin is only effective against susceptible bacterial infections, not viral illnesses 1
When prescribing cephalexin for a 3-year-old, carefully calculate the appropriate dose based on the child's weight and the specific infection being treated, and counsel parents on the importance of completing the full course of therapy.