Azithromycin: what it is and when to use it
Azithromycin is a widely used antibiotic in the macrolide family. It fights many bacterial infections like sinusitis, bronchitis, ear infections, certain skin infections, and sexually transmitted infections such as chlamydia. It works by stopping bacteria from making proteins they need to grow, so the infection can clear. This drug can be very convenient—often given as a short course—but only when used for the right kind of infection.
How to take azithromycin
Common dosing depends on the problem. For a standard "Z‑pack" adults often take 500 mg on day 1 followed by 250 mg once daily on days 2–5. For some respiratory or skin infections doctors may prescribe 500 mg once daily for 3 days. For chlamydia a single 1 g dose is usually used. Children get weight‑based doses (your pediatrician will calculate mg/kg). Take it exactly as prescribed—don’t skip doses and don’t stop early even if you feel better, unless your doctor tells you to.
Timing with food matters little for azithromycin, but antacids with aluminum or magnesium can lower how much drug your body absorbs if taken at the same time. If you take antacids, space them at least 2 hours apart from azithromycin.
Side effects, interactions and safety
Most people handle azithromycin well. The most common side effects are stomach upset, nausea, diarrhea, and sometimes headache. If you get severe diarrhea with blood or persistent belly pain, call your doctor—this can signal C. difficile infection, a serious but rare complication.
Azithromycin can affect heart rhythm in a small number of people. If you have a known heart rhythm problem, low potassium or magnesium, or take other drugs that prolong the QT interval (some antiarrhythmics, certain antipsychotics), tell your doctor first. Also mention blood thinners like warfarin—azithromycin can change how they work and your doctor may need to monitor you more closely.
Pregnant and breastfeeding people usually tolerate azithromycin but check with your provider before taking any antibiotic. If you have severe liver disease, share that history—doses or choices might change.
Resistance is real: azithromycin won’t help viral illnesses like colds or most sore throats. Using it when it’s not needed speeds up resistance. Never share antibiotics or use leftovers for a new illness.
If you miss a dose, take it as soon as you remember unless it’s nearly time for the next dose—then skip the missed one. Store tablets at room temperature away from moisture. If you notice an allergic reaction (rash, swelling, trouble breathing), seek urgent care.
Questions about whether azithromycin is right for you? Ask your doctor or pharmacist. Bring a list of medicines you take and your medical history so they can pick the safest option and dose.