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

Recommended Azithromycin Dosage for Pediatric Patients

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 most respiratory infections.

General Dosing Guidelines by Age and Indication

Infants <6 months

• For pertussis treatment and post-exposure prophylaxis: 10 mg/kg once daily for 5 days 1
• For infants <1 month with pertussis: azithromycin is the preferred macrolide due to lower risk of infantile hypertrophic pyloric stenosis compared to erythromycin 1

Children ≥6 months

• For community-acquired pneumonia (CAP):

  • 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) daily for days 2-5 1, 2
  • This regimen is recommended for presumed atypical pneumonia (Mycoplasma, Chlamydia) 1

• For acute otitis media:

  • Option 1: 30 mg/kg as a single dose 3
  • Option 2: 10 mg/kg once daily for 3 days 3
  • Option 3: 10 mg/kg on day 1, followed by 5 mg/kg daily for days 2-5 3

• For acute bacterial sinusitis:

  • 10 mg/kg once daily for 3 days 3

• For pharyngitis/tonsillitis:

  • 12 mg/kg once daily for 5 days (maximum 500 mg/day) 3
  • This higher dose is recommended due to potential for recurrence of infection with lower dosing 4

Weight-Based Dosing

For practical administration, the FDA provides the following weight-based dosing guidelines 3:

• 5 kg (11 lbs): 2.5 mL of 100 mg/5 mL suspension on day 1, then 1.25 mL on days 2-5
• 10 kg (22 lbs): 5 mL of 100 mg/5 mL suspension on day 1, then 2.5 mL on days 2-5
• 20 kg (44 lbs): 5 mL of 200 mg/5 mL suspension on day 1, then 2.5 mL on days 2-5
• 40 kg (88 lbs): 10 mL of 200 mg/5 mL suspension on day 1, then 5 mL on days 2-5

Efficacy and Safety Considerations

• Clinical studies show comparable efficacy between 3-day (10 mg/kg daily) and 5-day regimens (10 mg/kg on day 1,5 mg/kg on days 2-5) for respiratory infections, with clinical cure rates of 95.7% and 96.1% respectively 5

• Azithromycin is generally well-tolerated in children with adverse events reported in only 8.7% of children, mostly mild gastrointestinal disturbances 6

• For streptococcal pharyngitis, a higher dose of 12 mg/kg for 5 days is recommended due to lower bacterial eradication rates observed with the standard 10 mg/kg dosing 7

Important Precautions

• Azithromycin can be taken with or without food 3

• Avoid concurrent administration with aluminum- or magnesium-containing antacids as they reduce absorption 1, 2

• Monitor for potential drug interactions, particularly with medications that prolong QT interval 2

• For infants <1 month receiving azithromycin, monitor for infantile hypertrophic pyloric stenosis 1

• No dosage adjustment is recommended for patients with renal impairment (GFR ≤80 mL/min), though caution should be exercised in severe renal impairment 3