Keflex (Cephalexin) Dosing for Sinus Infection in a Seven-Year-Old Child
The recommended dose of Keflex (cephalexin) for a 7-year-old child with sinus infection is 25-50 mg/kg/day divided into 2-4 doses, typically given for 7-10 days. 1
Dosage Calculation
For a typical 7-year-old child (approximately 20-25 kg):
- Standard dose: 25-50 mg/kg/day
- For a 22 kg child: 550-1100 mg/day total
- Divided into either:
- Four times daily (q6h): 137.5-275 mg per dose
- Twice daily (q12h): 275-550 mg per dose
Administration Options
Option 1: Four times daily regimen
- 125-250 mg every 6 hours
- Equivalent to 1-2 teaspoons of 125 mg/5 mL suspension four times daily 1
Option 2: Twice daily regimen
- 250-500 mg every 12 hours
- Equivalent to 2-4 teaspoons of 125 mg/5 mL suspension twice daily 1
Treatment Considerations
Duration of Treatment
- Standard duration: 7-10 days 2
- Treatment should continue for at least 48-72 hours after symptom resolution
Special Considerations
- For severe infections, the dosage may be doubled 1
- In cases of otitis media (which may accompany sinusitis), higher doses of 75-100 mg/kg/day in 4 divided doses may be required 1
Alternative Antibiotics
If the child has risk factors for resistant organisms (daycare attendance, recent antibiotic use within past 30 days), consider:
- Amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component) 2
- Cefpodoxime-proxetil (8 mg/kg/day in two doses) 2
For penicillin-allergic patients:
- Cefdinir, cefuroxime, or cefpodoxime 2
- Avoid trimethoprim/sulfamethoxazole and azithromycin due to resistance patterns 2
Clinical Monitoring
- Assess for clinical improvement within 48-72 hours
- Signs of improvement include:
- Decreased nasal discharge
- Reduced cough
- Improved fever
- If symptoms worsen or don't improve after 72 hours, consider changing antibiotics 2
Potential Pitfalls and Caveats
Adherence challenges: Twice-daily dosing may improve adherence compared to four-times-daily dosing while maintaining similar efficacy 3
Resistance concerns: Be aware of local resistance patterns. In areas with high prevalence of resistant organisms, higher doses or alternative antibiotics may be needed 2
Differentiation from viral illness: Ensure the diagnosis meets criteria for bacterial sinusitis (symptoms persisting >10 days without improvement, worsening symptoms after initial improvement, or severe symptoms with fever ≥102.2°F and purulent nasal discharge for ≥3 days) 2
Storage of suspension: After reconstitution, the suspension must be refrigerated and used within 14 days 1
Side effects: Monitor for gastrointestinal symptoms and rare cases of neutropenia 4
The FDA-approved labeling for cephalexin provides clear guidance on dosing for pediatric patients, making it a reliable and effective option for treating sinus infections in children when bacterial etiology is confirmed.