What is the recommended dosage of azithromycin (macrolide antibiotic) for a 2-year-old child?

Azithromycin Dosing for a 2-Year-Old Child

For a 2-year-old child, administer azithromycin 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) once daily on days 2-5 for most indications, including community-acquired pneumonia and acute otitis media. 1, 2, 3

Standard Dosing by Indication

Community-Acquired Pneumonia (Atypical Pathogens)

• Use the 5-day regimen: 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2-5 1, 2, 3
• This regimen is specifically indicated for atypical pathogens including Mycoplasma pneumoniae, Chlamydia pneumoniae, and Chlamydia trachomatis 1, 2
• Critical caveat: Azithromycin is NOT first-line for typical bacterial pneumonia caused by S. pneumoniae or H. influenzae—amoxicillin remains the preferred agent for these pathogens 1, 2

Acute Otitis Media

The FDA label provides three acceptable regimens 3:

• 5-day regimen (preferred for consistency with other indications): 10 mg/kg day 1, then 5 mg/kg days 2-5 3
• 3-day regimen: 10 mg/kg once daily for 3 days 3
• Single-dose regimen: 30 mg/kg as a single dose 3, 4, 5

The single-dose regimen (30 mg/kg) demonstrates 88% clinical success and excellent compliance (99-100%), but is most appropriate when compliance is a concern or directly observed therapy is needed 4, 5

Pharyngitis/Tonsillitis

• Use a HIGHER dose: 12 mg/kg once daily for 5 days (maximum 500 mg/day) 1, 3
• Important: Azithromycin is second-line therapy only—penicillin or amoxicillin remains first-line for streptococcal pharyngitis 1, 2
• The higher 12 mg/kg dose is necessary because standard dosing results in high recurrence rates for strep throat 1

Acute Bacterial Sinusitis

• 10 mg/kg once daily for 3 days 3

Weight-Based Dosing for a Typical 2-Year-Old

For a 2-year-old weighing approximately 12 kg (26 lbs), using the 5-day regimen 3:

• Day 1: 5 mL of 200 mg/5 mL suspension (120 mg total)
• Days 2-5: 2.5 mL of 200 mg/5 mL suspension (60 mg daily)
• Total course: 15 mL suspension = 360 mg total

Administration Guidelines

Timing and Food

• Azithromycin oral suspension can be taken with or without food 3
• The pediatric oral suspension must be reconstituted with water before administration 1

Critical Drug Interactions to Avoid

• Do NOT administer simultaneously with aluminum- or magnesium-containing antacids—separate by at least 2 hours 1, 2
• These antacids significantly reduce azithromycin absorption 1, 2
• Monitor for QT prolongation when used with other QT-prolonging medications 2

Expected Clinical Response and Follow-Up

• Children should demonstrate clinical improvement within 48-72 hours of starting therapy 1
• If the patient deteriorates or shows no improvement within this timeframe, reassess for:
  • Complications such as parapneumonic effusion 1
  • Resistant organisms or incorrect diagnosis 1
  • Need for alternative antibiotic therapy 1

Safety Profile

Common Adverse Effects

• Gastrointestinal disturbances (abdominal discomfort, diarrhea, nausea, vomiting) are most common 1
• Dizziness and headache may occur 1
• Azithromycin has significantly fewer gastrointestinal side effects compared to erythromycin 1, 6, 7

Rare but Serious Adverse Effects

• Acute interstitial nephritis 1
• Allergic reactions/anaphylaxis 1
• Pseudomembranous colitis 1
• In infants <1 month, monitor for infantile hypertrophic pyloric stenosis (IHPS), though azithromycin has not been strongly associated with this condition 1

Common Pitfalls to Avoid

1. Do not use azithromycin as first-line for typical bacterial pneumonia or pharyngitis—beta-lactams remain first-line 1, 2
2. Do not underdose pharyngitis—requires 12 mg/kg daily, not the standard 5 mg/kg maintenance dose 1, 3
3. Do not co-administer with antacids—separate by at least 2 hours 1, 2
4. Do not continue IV therapy beyond 2 days when oral therapy is feasible (if IV therapy was initiated) 1, 2