Azithromycin Dosage for an 11-Month-Old Baby Girl
For an 11-month-old infant (≥6 months of age), administer azithromycin 10 mg/kg as a single dose on day 1, followed by 5 mg/kg once daily on days 2 through 5, with a maximum dose of 500 mg on day 1 and 250 mg on subsequent days. 1, 2, 3
Standard Dosing Regimen
The CDC-recommended dosing for infants ≥6 months is the 5-day regimen 1, 4:
- Day 1: 10 mg/kg once daily (maximum 500 mg)
- Days 2-5: 5 mg/kg once daily (maximum 250 mg)
This regimen applies to most common pediatric infections including community-acquired pneumonia, pertussis treatment/prophylaxis, and atypical respiratory infections 1, 2, 3.
Weight-Based Dosing Example
For practical administration using the oral suspension 3:
- If the infant weighs 10 kg (22 lbs):
- Day 1: 5 mL of 200 mg/5 mL suspension (100 mg total)
- Days 2-5: 2.5 mL of 200 mg/5 mL suspension (50 mg total) daily
- Total course: 15 mL delivering 300 mg
Alternative Regimens by Indication
While the 5-day regimen is standard, specific infections may warrant different approaches 2, 3:
Acute otitis media: Three alternative regimens are FDA-approved:
Acute bacterial sinusitis: 10 mg/kg once daily for 3 days 3
Important caveat: The 5-day regimen remains the most widely validated and is preferred for most indications, particularly respiratory infections 1, 2.
Administration Guidelines
- Azithromycin can be taken with or without food 3
- Do not administer simultaneously with aluminum- or magnesium-containing antacids, as they reduce absorption 1, 4, 2
- The oral suspension is well-tolerated with agreeable taste for children 5, 6
Safety Monitoring
Monitor for common adverse effects, which occur in approximately 9% of pediatric patients 4, 6:
- Gastrointestinal symptoms: nausea, vomiting, abdominal pain, diarrhea (most common) 1, 4, 7
- These effects are typically mild to moderate and rarely require discontinuation 5, 6, 7
For infants <6 months: While your patient is 11 months old, it's worth noting that infants <6 months receive 10 mg/kg once daily for 5 days (no loading dose) 1, 2. The CDC recommends monitoring these younger infants for infantile hypertrophic pyloric stenosis (IHPS), though azithromycin has lower risk than erythromycin 4, 2.
Common Pitfalls to Avoid
- Underdosing: Ensure the full 10 mg/kg loading dose is given on day 1, not 5 mg/kg 1, 3
- Drug interactions: Monitor if the infant is on medications metabolized by cytochrome P450 enzymes, digoxin, or triazolam 1, 2
- Hepatic impairment: Use with caution if liver dysfunction is present 1
- Renal impairment: No dose adjustment needed unless severe (GFR <10 mL/min), where caution is advised 3