What is the appropriate azithromycin dose for a 5‑year‑old child weighing 32 lb?

Azithromycin Dosing for a 5-Year-Old Weighing 32 Pounds

For a 5-year-old child weighing 32 pounds (14.5 kg), the recommended azithromycin dose is 10 mg/kg (145 mg) on day 1, followed by 5 mg/kg (72.5 mg) once daily on days 2–5 for respiratory tract infections such as community-acquired pneumonia. 1, 2

Weight-Based Calculation

• 32 pounds = 14.5 kg (conversion: 32 ÷ 2.2 = 14.5 kg) 1
• Day 1 dose: 10 mg/kg × 14.5 kg = 145 mg 1, 2
• Days 2–5 dose: 5 mg/kg × 14.5 kg = 72.5 mg once daily 1, 2

Practical Dosing Using Oral Suspension

• Using the 200 mg/5 mL suspension, administer approximately 3.6 mL on day 1 and 1.8 mL once daily on days 2–5 2
• The FDA-approved pediatric dosing table for a child weighing 10 kg (22 lb) recommends 5 mL (200 mg) on day 1 and 2.5 mL (100 mg) on days 2–5; for a 20 kg (44 lb) child, 5 mL (200 mg) on day 1 and 2.5 mL (100 mg) on days 2–5 using the 200 mg/5 mL formulation 2
• For this 14.5 kg child, the dose falls between these weight bands, so approximately 3.6 mL on day 1 and 1.8 mL daily thereafter is appropriate 2

Indication-Specific Considerations

Community-Acquired Pneumonia

• Azithromycin is specifically indicated for atypical pathogens (Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia trachomatis) 1
• For typical bacterial pneumonia caused by Streptococcus pneumoniae or Haemophilus influenzae, amoxicillin 90 mg/kg/day remains first-line therapy; azithromycin should not be used as monotherapy 1

Acute Otitis Media

• For otitis media, the FDA label permits alternative regimens: 30 mg/kg as a single dose (435 mg), or 10 mg/kg once daily for 3 days (145 mg daily), or the standard 5-day regimen 2

Pharyngitis/Tonsillitis

• Azithromycin is second-line therapy only for strep throat; penicillin or amoxicillin remain first-line 1
• If used for pharyngitis, a higher dose of 12 mg/kg once daily for 5 days (174 mg daily) is necessary due to high recurrence rates with the standard 10 mg/kg regimen 1, 2, 3

Expected Clinical Response

• Children on appropriate azithromycin therapy should demonstrate clinical improvement within 48–72 hours 1
• If no improvement or clinical deterioration occurs within this timeframe, reassess the diagnosis, consider alternative pathogens, resistance patterns, or complications, and adjust therapy accordingly 1

Administration Guidelines

• Azithromycin can be taken with or without food, though administration with meals may improve gastrointestinal tolerability 2
• Do not administer simultaneously with aluminum- or magnesium-containing antacids; separate by at least 2 hours, as antacids reduce drug absorption 1, 2

Common Pitfalls to Avoid

• Do not underdose the initial 10 mg/kg dose on day 1; full dosing is essential to achieve therapeutic tissue levels 1
• Do not prescribe azithromycin as first-line treatment for typical bacterial pneumonia or streptococcal pharyngitis, as β-lactam agents have superior outcomes and lower recurrence rates 1
• Ensure the correct indication: azithromycin is reserved for atypical pathogens or documented penicillin allergy 1

Safety Profile

• Common adverse effects include gastrointestinal disturbances (abdominal discomfort, diarrhea, nausea, vomiting), dizziness, and headache 1, 2
• Azithromycin has fewer gastrointestinal side effects compared to erythromycin 1, 3
• For prolonged courses, monitor ECG for QT prolongation and consider baseline and intermittent audiometry 1