Azithromycin — Antibiotic Guide | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is azithromycin?
Azithromycin is a macrolide antibiotic used to treat bacterial infections. It is commonly prescribed for chest infections (community-acquired pneumonia), skin infections, sexually transmitted infections (chlamydia), and ear infections. Brand names in NZ include Zithromax and various generics.
What is it used for? (NZ context)
Azithromycin treats respiratory tract infections (chest infections, sinusitis), skin infections, chlamydia and some other STIs, and ear infections. A common NZ regimen is a 3-day course (500mg once daily) or a single 1g dose for chlamydia. It is funded by Pharmac.
How does it work?
Azithromycin binds to the 50S ribosomal subunit of bacteria, blocking protein synthesis and preventing bacterial growth (bacteriostatic). It has good tissue penetration and accumulates inside cells, giving it a long tissue half-life — which is why short courses (3–5 days) are effective.
How to take it
Azithromycin can be taken with or without food. Follow your prescribed course and complete the full prescription even if you feel better early. For chlamydia, 1g is taken as a single dose. The 3-day course (500mg daily) is common for chest infections.
Common side effects
- Nausea and stomach upset — most common
- Diarrhoea
- Stomach cramps
- Vomiting
Serious side effects to watch for
Azithromycin can rarely cause cardiac arrhythmias (particularly QT prolongation). People with pre-existing heart conditions or taking other QT-prolonging medicines should use it with caution. Serious liver problems are rare but possible. Allergic reactions including anaphylaxis are uncommon but possible.
Important drug interactions
Warfarin — azithromycin can increase INR; monitor closely. Antacids containing aluminium or magnesium — take azithromycin 1 hour before or 2 hours after antacids. Other QT-prolonging medicines — increased cardiac risk. Avoid combining with other QT-prolonging drugs where possible.
NZ-specific information
Pharmac funding: Azithromycin 250mg and 500mg tablets and 1g sachets (for chlamydia) are funded by Pharmac. Multiple generic brands are available across NZ pharmacies.
Frequently asked questions
Why is azithromycin given for only 3 days when other antibiotics are 7 days?
Azithromycin builds up in tissues at high concentrations and stays there for several days after the last dose. Effective tissue levels persist for up to 7–10 days after a 3-day course, achieving the same result as a longer course of other antibiotics.
Can azithromycin treat COVID-19?
No — azithromycin is not effective for COVID-19. Early in the pandemic some studies suggested possible benefit, but subsequent large trials showed no benefit over placebo. It is only effective against bacterial infections.
Can I drink alcohol on azithromycin?
Alcohol does not directly interact with azithromycin, but it can worsen nausea and stomach upset (already common side effects of azithromycin) and may impair recovery from infection. Moderate intake is generally fine, but avoid excess.
💬 Talk to your pharmacist or doctor for personalised advice about azithromycin.
Reviewed by a Registered Pharmacist NZ | BPharm, Pharmacy Council of New Zealand
References & Further Information
The following New Zealand and international resources were used to inform this page: