Azithromycin is an antibiotic.

It’s widely used to treat chest infections such as pneumonia, infections of the nose and throat such as sinusitis, skin infections, Lyme disease, and some sexually transmitted infections.

Azithromycin is used in children, often to treat ear infections or chest infections.

It can also be used long term to prevent chest infections in people who keep getting them.

The medicine is available on prescription as capsules, tablets and a liquid that you drink. It can also be given by injection, but this is usually only done in hospital.

  • Azithromycin is usually taken once a day. Try to take it at the same time each day.
  • If your doctor has prescribed azithromycin capsules, you should take them at least 1 hour before food or 2 hours after. If you have tablets or liquid, you can take them with or without food.
  • For most infections you should feel better within a few days, but you should still finish your full course of medicine.
  • The most common side effects of azithromycin are feeling sick, diarrhoea or vomiting, headache, or changes to your sense of taste.
  • Azithromycin is also called by the brand name Zithromax.

Azithromycin can be taken by adults and children.

It isn’t suitable for some people. To make sure azithromycin is safe for you, tell your doctor if you have:

  • had an allergic reaction to azithromycin or any other medicines in the past
  • liver or kidney problems
  • heart problems, including irregular heartbeats (arrhythmias)
  • had diarrhoea when you have taken antibiotics before
  • myasthenia gravis – azithromycin can worsen the symptoms of this muscle-weakening illness
  • diabetes – azithromycin liquid contains sugar

Azithromycin is usually taken once a day, unless you’re having it by injection. Try to take your medicine at the same time each day.

The usual dose is 500mg a day for 3 to 10 days depending on the infection being treated.

For some infections, you’ll be given a one-off higher dose of 1g or 2g.

The dose may be lower for children or if you have liver or kidney problems.

Azithromycin is sometimes prescribed long term to prevent chest infections if you keep getting them. In this case, it’s usually taken 3 times a week, often on a Monday, Wednesday and Friday.

Like all medicines, azithromycin can cause side effects, although not everyone gets them.

Common side effects

These common side effects of azithromycin happen in more than 1 in 100 people.

Keep taking the medicine, but talk to your doctor or pharmacist if these side effects bother you or don’t go away:

  • feeling sick
  • diarrhoea or vomiting
  • losing your appetite
  • headache
  • feeling dizzy or tired
  • changes to your sense of taste

Serious side effects

Serious side effects are rare and happen in less than 1 in 1,000 people.

Tell a doctor straight away if you get:

  • chest pains or a faster or irregular heartbeat
  • yellow skin or the whites of your eyes turn yellow, or pale poo with dark pee – these can be signs of liver or gallbladder problems
  • ringing in your ears (tinnitus), temporary hearing loss, or you feel unsteady on your feet (vertigo)
  • severe pain in your tummy or back – these can be warning signs of inflammation of the pancreas (pancreatitis)
  • severe or long-lasting diarrhoea with blood in your poo

Serious allergic reaction

In rare cases, it’s possible to have a serious allergic reaction to azithromycin.

What to do about:

  • feeling sick – stick to simple meals and don’t eat rich or spicy food while you’re taking this medicine
  • diarrhoea and vomiting – drink plenty of water or other liquids if you have diarrhoea or you’re being sick. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor.
  • losing your appetite – eat when you would usually expect to be hungry. If it helps, eat smaller meals more often than usual. Snack when you’re hungry. Have nutritious snacks that are high in calories and protein, such as dried fruit and nuts.
  • headache – rest and drink plenty of water. Ask your pharmacist to recommend a painkiller if you need one. Talk to your doctor if the headaches last longer than a week or are severe.
  • feeling dizzy or tired – if you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so you don’t faint, then sit until you feel better. Don’t drive or use tools or machines if you feel dizzy or tired. Don’t drink alcohol as it may make you feel worse.
  • changes to your sense of taste – talk with your doctor if this is bothering you

Azithromycin isn’t normally recommended during pregnancy or while breastfeeding. But your doctor may prescribe it if the benefits of taking azithromycin are greater than the risks.

There are some medicines that don’t mix well with azithromycin.

Tell your doctor if you’re taking these medicines before you start azithromycin:

  • antacids for indigestion
  • ergotamine or dihydroergotamine – for migraine
  • warfarin – to thin blood or prevent blood clots
  • ciclosporin or tacrolimus – medicines to stop your immune system overreacting
  • colchicine for gout
  • digoxin for some heart problems
  • rifabutin – an antibiotic
  • nelfinavir – a medicine for HIV
  • a statin medicine to lower your cholesterol – such as simvastatin and atorvastatin

You should also let your doctor know if you’re taking any medicines for an irregular heartbeat (arrhythmia), such as amiodarone or sotalol.

Azithromycin can sometimes affect your heartbeat, so it’s best not to take it with other medicines that have the same side effect.

For this reason, it’s important that you tell your doctor if you’re taking medicines that can affect your heartbeat as a side effect.

These can include:

  • antidepressants – such as citalopram
  • antipsychotics – used to treat severe mental health problems
  • some antisickness medicines – such as domperidone
  • some antibiotics – such as moxifloxacin

Check the leaflets that come with your medicines and talk to a pharmacist or your doctor if you have any worries.

Mixing azithromycin with herbal remedies and supplements

There are no known problems with taking herbal remedies or supplements alongside azithromycin.

How does azithromycin work?