Pediatric Azithromycin Dose

Pediatric azithromycin dosing by weight

Azithromycin is a macrolide antibiotic, and in children it comes into play when there's a beta-lactam allergy or you need to cover atypical pathogens (Mycoplasma, Chlamydia, pertussis). Two pediatric regimens show up most often: 10 mg/kg/day × 3 days or 12 mg/kg/day on day 1, then 6 mg/kg/day for 4 days (a 5-day course adding up to 30 mg/kg). The classic pediatric suspension (e.g. Zitromax) is 200 mg/5 mL and is given as a single daily dose. To get the volume per dose in mL, use (mg per dose ÷ 200) × 5 mL.

Safety disclaimer: azithromycin is a controlled antibiotic under ANVISA RDC 20/2011, so it needs a medical prescription with the second copy retained. Don't self-medicate. It feeds the already rising tide of macrolide resistance, can stretch the QT interval and raise the risk of arrhythmia, and it interacts with quite a few other drugs. Talk to a paediatrician first.

Applications

In outpatient pediatrics it shows up for atypical pneumonia, pertussis, cervicofacial infections in penicillin-allergic patients and traveller's diarrhoea, plus it features in HIV post-exposure prophylaxis (PEP) protocols when indicated. A dose calculator does two things here: it turns mg/kg into mL of suspension and it keeps you on the once-daily schedule, which sets azithromycin apart from amoxicillin. References: SBP, WHO, AAP/IDSA and ANVISA RDC 20/2011.

FAQ

Why is azithromycin once-daily? It has a long intracellular half-life, around 68 h, so therapeutic levels hold up even after the last dose. That's what makes single daily dosing and short 3–5 day courses possible.

Can I use azithromycin for any cold or flu? No. Antibiotics do nothing against viral infections, and using them anyway just breeds resistance and brings side effects. The decision is the doctor's, based on clinical and/or lab evidence that the infection is bacterial.

What are the most common side effects? Mostly diarrhoea, abdominal pain and nausea, with a transient rise in transaminases now and then. If palpitations, syncope or jaundice come up, stop and get medical care.