What is the pediatric azithromycin dose for pertussis treatment, pertussis prophylaxis, and for acute otitis media, acute bacterial sinusitis, community‑acquired pneumonia, or skin‑soft‑tissue infections?

Pediatric Azithromycin Dosing

Pertussis Treatment

For infants <6 months with pertussis, administer azithromycin 10 mg/kg per day for 5 consecutive days. 1, 2

For children ≥6 months with pertussis, administer azithromycin 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg per day (maximum 250 mg) on days 2-5. 1

• Azithromycin is the preferred first-line agent for all pediatric age groups due to significantly lower risk of infantile hypertrophic pyloric stenosis (IHPS) compared to erythromycin, particularly critical in infants <1 month. 1
• Start treatment immediately upon clinical suspicion without waiting for culture confirmation, as early treatment (within first 2 weeks) rapidly clears B. pertussis from the nasopharynx and decreases coughing paroxysms. 1
• After 3 weeks of symptoms, antibiotics have limited clinical benefit but remain indicated to prevent transmission. 1
• Do not administer azithromycin simultaneously with aluminum- or magnesium-containing antacids as they reduce absorption. 1, 2

Pertussis Prophylaxis (Postexposure)

Use identical dosing regimens as treatment: 10 mg/kg/day for 5 days in infants <6 months, or 10 mg/kg (max 500 mg) day 1 then 5 mg/kg/day (max 250 mg) days 2-5 in children ≥6 months. 1

• Prioritize prophylaxis for all close contacts, especially in households with infants <12 months or women in third trimester of pregnancy. 1
• Administer within 21 days of exposure for maximum effectiveness. 1

Acute Otitis Media

Administer azithromycin 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg per day (maximum 250 mg) on days 2-5. 3

• Alternative single-dose regimen: 30 mg/kg as a one-time dose shows 88% end-of-treatment clinical success, particularly useful when compliance is a concern or directly observed therapy is needed. 4
• Clinical success rates: 79.6-82.4% at day 11 for S. pneumoniae, H. influenzae, and M. catarrhalis infections with the 5-day regimen. 5
• Important caveat: Azithromycin is generally not recommended as first-line for acute otitis media due to concerns about pneumococcal resistance; reserve for penicillin-allergic patients or when compliance with other regimens is problematic. 6

Acute Bacterial Sinusitis

Use the same dosing as acute otitis media: 10 mg/kg (maximum 500 mg) on day 1, followed by 5 mg/kg per day (maximum 250 mg) on days 2-5. 7, 8

Community-Acquired Pneumonia (Atypical Pathogens)

For children <5 years with presumed atypical pneumonia (outpatient): azithromycin 10 mg/kg on day 1, followed by 5 mg/kg per day once daily on days 2-5. 3

For children ≥5 years with presumed atypical pneumonia (outpatient): azithromycin 10 mg/kg on day 1 (maximum 500 mg), followed by 5 mg/kg per day (maximum 250 mg) on days 2-5. 3

For hospitalized children (all ages) with suspected atypical pneumonia: administer azithromycin in addition to β-lactam therapy if diagnosis is in doubt. 3

• Azithromycin targets Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species. 3, 7
• For children ≥5 years without clear distinction between bacterial and atypical pneumonia, add azithromycin to amoxicillin for empiric coverage. 3
• Critical distinction: Azithromycin should be avoided as monotherapy for pneumococcal pneumonia due to resistance concerns; use β-lactams as first-line for presumed bacterial pneumonia. 3, 6

Skin and Soft Tissue Infections

Administer azithromycin 10 mg/kg on day 1, followed by 5 mg/kg per day on days 2-5, OR use a 3-day course of 10 mg/kg per day. 7, 8

• Both the 3-day (10 mg/kg/day) and 5-day regimens (10 mg/kg day 1, then 5 mg/kg/day days 2-5) demonstrate comparable efficacy to cefaclor, dicloxacillin, and flucloxacillin. 7
• Azithromycin is effective against S. pyogenes, S. agalactiae, and methicillin-susceptible S. aureus. 7
• Avoid azithromycin in patients with significant risk of bacteremia, as tissue-selective pharmacokinetics may result in inadequate serum concentrations. 6

Key Safety Considerations Across All Indications

• Monitor infants <6 months receiving any macrolide for signs of IHPS (projectile vomiting, visible peristaltic waves, palpable olive-shaped mass in epigastrium), though risk is significantly lower with azithromycin than erythromycin. 1, 2
• Unlike erythromycin and clarithromycin, azithromycin does NOT inhibit cytochrome P450 enzymes, minimizing drug-drug interactions. 1
• Obtain baseline ECG in patients taking QTc-prolonging medications (e.g., citalopram) before initiating azithromycin. 1
• Isolate patients for 5 days after starting antibiotics to prevent transmission in pertussis cases. 1