Azithromycin Syrup Dosing for Pediatric Patients
For most common pediatric infections, azithromycin oral suspension is 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, 2
Standard 5-Day Regimen by Weight
This is the preferred regimen for community-acquired pneumonia, atypical respiratory infections (Mycoplasma, Chlamydia), and most respiratory tract infections in children ≥6 months:
| Weight | Day 1 Dose | Days 2–5 Dose | Total Course |
|---|---|---|---|
| 5 kg (11 lbs) | 2.5 mL | 1.25 mL daily | 150 mg |
| 10 kg (22 lbs) | 5 mL | 2.5 mL daily | 300 mg |
| 20 kg (44 lbs) | 5 mL (200 mg/5 mL)* | 2.5 mL daily | 600 mg |
| 30 kg (66 lbs) | 7.5 mL | 3.75 mL daily | 900 mg |
| 40 kg (88 lbs) | 10 mL | 5 mL daily | 1200 mg |
| ≥50 kg (≥110 lbs) | 12.5 mL | 6.25 mL daily | 1500 mg |
*Use 200 mg/5 mL concentration for children >15 kg 2, 1
Alternative Weight-Band Dosing (British Thoracic Society)
For children 6 months–17 years, simplified once-daily dosing for 5 days: 3, 1
- 15–25 kg: 200 mg once daily
- 26–35 kg: 300 mg once daily
- 36–45 kg: 400 mg once daily
- ≥46 kg: 500 mg once daily
Indication-Specific Dosing
Acute Otitis Media
Three FDA-approved regimens exist: 2
- 5-day regimen (preferred): 10 mg/kg day 1, then 5 mg/kg days 2–5
- 3-day regimen: 10 mg/kg once daily for 3 days
- Single-dose regimen: 30 mg/kg as a single dose
However, azithromycin is second-line for acute otitis media—amoxicillin 80–90 mg/kg/day remains first-line. 1 Reserve azithromycin for documented β-lactam allergy. 4
Streptococcal Pharyngitis
Azithromycin is second-line only; penicillin or amoxicillin remain first-line. 1 When azithromycin is necessary (documented penicillin allergy), use 12 mg/kg once daily for 5 days (maximum 500 mg/day) due to high recurrence rates with standard 10 mg/kg dosing. 1, 2, 5
Pertussis (Treatment or Post-Exposure Prophylaxis)
- Infants <6 months: 10 mg/kg once daily for 5 days 1
- Children ≥6 months: 10 mg/kg day 1, then 5 mg/kg days 2–5 1
Mycobacterium Avium Complex (MAC) Prophylaxis in HIV
20 mg/kg once weekly (maximum 1,200 mg) 3, 1
Administration Guidelines
- Can be taken with or without food 2, 1
- Do NOT give simultaneously with aluminum- or magnesium-containing antacids—separate by at least 2 hours, as antacids reduce absorption 1, 2
- Oral suspension must be reconstituted with water before administration 1
Expected Clinical Response
Children should demonstrate clinical improvement within 48–72 hours. 1 If no improvement or clinical deterioration occurs within this window, reassess the diagnosis, consider alternative pathogens (including typical bacteria requiring β-lactam therapy), evaluate for complications (e.g., parapneumonic effusion), and adjust therapy accordingly. 1
Critical Pitfalls to Avoid
Do not underdose the initial 10 mg/kg dose on day 1—full loading is essential to achieve therapeutic tissue levels. 1
Do not use azithromycin as first-line for typical bacterial pneumonia (S. pneumoniae, H. influenzae) or streptococcal pharyngitis—amoxicillin has superior outcomes and lower recurrence rates. 1
Azithromycin is specifically indicated for atypical pathogens (Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia trachomatis) or documented β-lactam allergy. 1
For strep throat, the standard 10 mg/kg regimen fails frequently—use 12 mg/kg daily for 5 days instead. 1, 5
Verify suspension concentration (100 mg/5 mL vs 200 mg/5 mL) before calculating volume to avoid dosing errors. 2
Safety Considerations
- Common adverse effects: Gastrointestinal disturbances (abdominal discomfort, diarrhea, nausea, vomiting), dizziness, headache 1
- Azithromycin has fewer GI side effects than erythromycin 1, 6
- Can prolong QT interval—obtain baseline ECG for prolonged courses (e.g., MAC prophylaxis) and repeat at 2 weeks or when adding QT-prolonging medications 1
- FDA Pregnancy Category B 1
- Use caution in severe hepatic impairment (biliary excretion is the main elimination route) 1
Age Restrictions
Azithromycin is safe and effective in children ≥6 months for most indications. 1, 2 For infants <1 month with pertussis, azithromycin 10 mg/kg once daily for 5 days is preferred over erythromycin due to lower risk of infantile hypertrophic pyloric stenosis (IHPS). 1