Azithromycin: Uses, Dosage, Side Effects, and Precautions

Azithromycin (Zithromax, Z-Pak): Comprehensive Guide

Indications

• Community-acquired pneumonia, acute bacterial sinusitis, acute otitis media.
• Pharyngitis/tonsillitis (Group A Strep).
• Skin/soft tissue infections (cellulitis, impetigo).
• STIs: Chlamydia (1 g single dose), gonorrhea (dual therapy), chancroid.
• Mycobacterium avium complex (MAC) prophylaxis in advanced HIV.
• Traveler’s diarrhea, pertussis, legionellosis, babesiosis (combination).

Mechanism

Binds 50S ribosomal subunit → inhibits bacterial protein synthesis (bacteriostatic). Long half-life (~68 hrs) allows short courses.

Common Dosage Regimens

• Adults: 500 mg day 1, then 250 mg daily × 4 days (5-day pack) for respiratory/skin infections.
• Chlamydia: 1 g single dose.
• Gonorrhea: 2 g single dose (with ceftriaxone).
• Pediatrics: 10 mg/kg day 1, then 5 mg/kg daily × 4 days (max 500 mg/day).

Key Side Effects

• GI: Nausea, diarrhea, abdominal pain (10–15%). Take with food to reduce.
• QT prolongation: Risk of torsades de pointes; avoid with other QT-prolonging drugs, electrolyte abnormalities.
• Hepatotoxicity: Rare; monitor LFTs if prolonged use.
• Hearing loss: Rare, usually reversible.
• C. difficile colitis: As with any antibiotic.

Precautions

• Pregnancy: Category B (safe).
• Renal/hepatic impairment: Dose adjustment rarely needed.
• Drug interactions: Antacids (aluminum/magnesium) reduce absorption—separate by 2 hrs. Digoxin, warfarin, statins, colchicine levels may increase.