Azithromycin: what it treats and how to use it safely
Azithromycin (often sold as Zithromax) is a macrolide antibiotic doctors prescribe for respiratory infections, some ear and skin infections, and certain sexually transmitted infections like chlamydia. It's popular because short courses can be effective and it usually causes fewer stomach problems than older macrolides. But being common doesn't mean it's harmless—use it only when a clinician says so.
How azithromycin works and common uses
Azithromycin stops bacteria by blocking their protein-making machinery. That makes it useful against community-acquired pneumonia, bronchitis when bacteria are suspected, sinusitis, strep throat (sometimes), some ear infections, and atypical bugs like Mycoplasma or Legionella. Doctors also use a single 1 g dose for uncomplicated chlamydia. Which bug it targets and how long you take it depends on the diagnosis.
How to take azithromycin — practical tips
Typical adult regimens: either 500 mg once on day 1 then 250 mg daily for four more days, or 500 mg once daily for three days for some infections. For chlamydia, one 1 g dose is common. For kids the dose is weight-based (commonly 10 mg/kg on day 1, then 5 mg/kg on following days), but follow your pediatrician's instructions. Always finish the prescribed course unless your doctor tells you to stop.
Take azithromycin with or without food. If you use antacids with aluminum or magnesium, take azithromycin at least 1–2 hours before or after the antacid to keep it working well. Store tablets at room temperature away from moisture.
Side effects, interactions, and red flags
Most people get mild side effects like diarrhea, nausea, or stomach pain. Serious but rare problems include severe allergic reactions, liver issues (look for yellow skin or dark urine), and heart rhythm changes—azithromycin can lengthen the QT interval. If you have a history of heart rhythm problems, low potassium or magnesium, or take other QT-prolonging drugs, tell your doctor first.
Azithromycin has fewer CYP450 interactions than some macrolides, but it can still interact with certain medications. Mention blood thinners (like warfarin), antiarrhythmics, and other prescription drugs to your prescriber or pharmacist. If you notice fast or irregular heartbeat, severe diarrhea (especially with fever or blood), rash, or breathing trouble, seek medical help right away.
One last point: antibiotics drive resistance when overused. Azithromycin won't help colds or flu, which are viral. Ask your clinician if an antibiotic is necessary. If they prescribe azithromycin, follow the dose, watch for side effects, and speak up about any concerns.
