What is the recommended dose of azithromycin (macrolide antibiotic) for pediatric pneumonia?

Azithromycin Dosing for Pediatric Pneumonia

For pediatric community-acquired pneumonia, azithromycin should be dosed at 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg (maximum 250 mg) once daily on days 2-5. 1

Clinical Context: When to Use Azithromycin

Azithromycin is not first-line therapy for typical bacterial pneumonia in children. 2

• Amoxicillin (90 mg/kg/day in 2 divided doses) remains the first-line agent for presumed bacterial pneumonia caused by Streptococcus pneumoniae or Haemophilus influenzae. 1

• Azithromycin is specifically indicated for atypical pneumonia caused by Mycoplasma pneumoniae, Chlamydophila pneumoniae, or Chlamydia trachomatis. 1

• For children ≥5 years with pneumonia where bacterial versus atypical etiology cannot be distinguished clinically, radiographically, or by laboratory testing, a macrolide can be added to amoxicillin for empiric dual coverage. 1

Standard Dosing Regimen

Outpatient Oral Therapy

5-Day Regimen (Preferred): 1, 2, 3, 4

• Day 1: 10 mg/kg orally (maximum 500 mg)
• Days 2-5: 5 mg/kg orally once daily (maximum 250 mg)

This dosing applies to children ≥6 months of age. 2, 3, 4

Inpatient IV Therapy

When parenteral therapy is required for atypical pneumonia: 1, 3

• Days 1-2: 10 mg/kg IV once daily (maximum 500 mg per dose)
• Transition to oral therapy as soon as clinically feasible using the standard 5 mg/kg daily dosing to complete the course. 1, 3

Critical pitfall: Do not continue IV azithromycin beyond days 1-2 when oral therapy is tolerated. 2, 3

Age-Specific Considerations

• Infants <6 months: Azithromycin dosing for pneumonia in this age group is less well-established; the standard 10 mg/kg day 1, then 5 mg/kg days 2-5 regimen is recommended by the Infectious Diseases Society of America. 1, 3

• Children ≥6 months: Standard 5-day regimen as above. 2, 3, 4

• Children >7 years: Doxycycline (2-4 mg/kg/day in 2 divided doses) is an alternative for atypical pneumonia. 1

Alternative Macrolides

If azithromycin is unavailable or not tolerated: 1, 3

• Clarithromycin: 15 mg/kg/day in 2 divided doses for 7-14 days (maximum 1 g/day)
• Erythromycin: 40 mg/kg/day in 4 divided doses

Azithromycin has fewer gastrointestinal side effects than erythromycin and offers the convenience of once-daily dosing. 3, 5, 6

Clinical Monitoring and Expected Response

• Children on appropriate therapy should demonstrate clinical improvement within 48-72 hours. 1

• If the patient deteriorates or shows no improvement within 48-72 hours, further investigation is mandatory to reassess the diagnosis and consider alternative pathogens (including Staphylococcus aureus, including CA-MRSA). 1

Safety Considerations and Common Pitfalls

Drug interactions to avoid: 2, 3

• Do not administer azithromycin simultaneously with aluminum- or magnesium-containing antacids, as they reduce absorption
• Monitor for QT prolongation when used with other QT-prolonging medications

Common adverse effects: 3, 6

• Gastrointestinal complaints (abdominal discomfort, diarrhea, nausea) occur in approximately 9% of patients
• Side effects are typically mild to moderate and rarely require discontinuation

Dosing errors to avoid: 2, 3

• Do not underdose—ensure the full 10 mg/kg loading dose on day 1
• Do not exceed maximum adult doses (500 mg day 1,250 mg days 2-5)
• Azithromycin can be taken with or without food 4

Treatment Duration

• Standard course is 5 days total (10 mg/kg day 1, then 5 mg/kg days 2-5). 1, 2, 3, 4

• Treatment courses of 10 days have been most extensively studied, but shorter 5-day courses are equally effective for mild to moderate disease managed outpatient. 1

• Infections caused by CA-MRSA may require longer treatment than typical pneumococcal pneumonia. 1