What is the recommended dose of azithromycin (Zithromax) for pediatric patients?

Pediatric Azithromycin Dosing Guidelines

The recommended dosage of azithromycin for pediatric patients varies by indication, with the most common regimen being 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) daily for days 2-5 for respiratory infections including community-acquired pneumonia. 1, 2

Dosing by Indication

Community-Acquired Pneumonia

• For presumed atypical pneumonia in outpatient setting:
  • Children <5 years: 10 mg/kg on day 1, followed by 5 mg/kg/day once daily on days 2-5 1
  • Children ≥5 years: 10 mg/kg on day 1 (maximum 500 mg), followed by 5 mg/kg/day once daily on days 2-5 (maximum 250 mg) 1, 2
• For inpatient treatment (all ages): Azithromycin should be added to β-lactam therapy if atypical pneumonia is suspected 1

Acute Otitis Media

• Three dosing options are available:
  • 30 mg/kg as a single dose (1-day regimen) 3
  • 10 mg/kg once daily for 3 days (3-day regimen) 3
  • 10 mg/kg on day 1, followed by 5 mg/kg/day on days 2-5 (5-day regimen) 3

Acute Bacterial Sinusitis

• 10 mg/kg once daily for 3 days 3

Pharyngitis/Tonsillitis

• 12 mg/kg once daily for 5 days (maximum 500 mg/day) 3, 4
  • Note: The higher dose of 12 mg/kg is specifically recommended for pharyngitis/tonsillitis due to potential for recurrence with lower dosing 5, 4

Other Indications

• Pertussis treatment and post-exposure prophylaxis:
  • Infants <6 months: 10 mg/kg once daily for 5 days 2
  • Children ≥6 months: 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) daily for days 2-5 2
• Mycobacterium avium complex (MAC) prophylaxis in HIV-infected children: 20 mg/kg body weight (maximum 1,200 mg) by mouth weekly 2

Weight-Based Dosing Chart

For standard 5-day regimen (10 mg/kg day 1,5 mg/kg days 2-5):

• 5 kg: 2.5 mL of 100 mg/5 mL suspension on day 1.25 mL on days 2-5 (total 150 mg) 3
• 10 kg: 5 mL of 100 mg/5 mL suspension on day 1,2.5 mL on days 2-5 (total 300 mg) 3
• 20 kg: 5 mL of 200 mg/5 mL suspension on day 1,2.5 mL on days 2-5 (total 600 mg) 3
• 40 kg: 10 mL of 200 mg/5 mL suspension on day 1,5 mL on days 2-5 (total 1200 mg) 3
• ≥50 kg: 12.5 mL of 200 mg/5 mL suspension on day 1,6.25 mL on days 2-5 (total 1500 mg) 3

Clinical Considerations

• Azithromycin can be taken with or without food 3
• The long half-life (approximately 32 hours in children) allows for once-daily dosing and sustained tissue concentrations 6
• Clinical success rates for the 5-day regimen in respiratory infections typically exceed 90% 5, 7
• For single-dose therapy (30 mg/kg) in acute otitis media, clinical success rates of 88% have been reported 8

Important Cautions

• Avoid concurrent administration with aluminum- or magnesium-containing antacids as they reduce absorption 2
• For streptococcal pharyngitis, the higher dose of 12 mg/kg for 5 days is necessary to prevent recurrence 4
• For children with macrolide-resistant S. pneumoniae infections, clinical success rates may be lower (67% vs 90% for susceptible strains) 8
• Alternative options for children allergic to azithromycin include clarithromycin (15 mg/kg/day in 2 doses), erythromycin (40 mg/kg/day in 4 doses), and doxycycline (for children >7 years old) 1, 2

The convenient once-daily dosing and short treatment duration of azithromycin make it particularly useful for pediatric patients where compliance may be challenging 5, 8.