﻿ Azithromycin: antibiotic to treat bacterial infections - NHS Skip to main content


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  1. About azithromycin
  2. Key facts
  3. Who can and cannot take azithromycin
  4. How and when to take it
  5. Side effects
  6. How to cope with side effects
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions

1. About azithromycin

Azithromycin is an antibiotic.





2. Key facts

  • 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 eating. 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 or being sick, diarrhoea, headaches, or changes to your sense of taste.
  • Azithromycin is also called by the brand name Zithromax.

3. Who can and cannot take azithromycin

Azithromycin can be taken by adults and children.


  • liver or kidney problems
  • heart problems, including irregular heartbeats (arrhythmia)
  • 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

4. How and when to take it


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.


Carry on taking this medicine until the course is completed, even if you feel better. If you stop your treatment early, your infection could come back.

How to take it



Swallow tablets and capsules whole with a glass of water.

Azithromycin liquid is available for children and people who find it difficult to swallow tablets.

If you or your child are taking azithromycin as a liquid, it'll usually be made up for you by your pharmacist. The medicine will come with a syringe or spoon to help you measure the right amount. If you don't have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give the right amount.

The liquid can have a bitter aftertaste, so it can be a good idea to offer children a drink of fruit juice afterwards.

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it's nearly time for your next one. In this case, just leave out the missed dose and take your next dose as normal.


If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for other ways to remember your medicine.

What if I take too much?


Talk to your pharmacist or doctor if you're worried, or if you or your child accidentally take more than 1 extra dose.

5. Side effects

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 (nausea)
  • diarrhoea or being sick (vomiting)
  • losing your appetite
  • headaches
  • feeling dizzy or tired
  • changes to your sense of taste

Serious side effects


Call 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 stomach or back - these can be warning signs of inflammation of the pancreas (pancreatitis)
  • diarrhoea (perhaps with muscle cramps) that contains blood or mucus - if you have severe diarrhoea without blood or mucus for more than 4 days you should also speak to a doctor

Serious allergic reaction

In rare cases it's possible to have a serious allergic reaction (anaphylaxis) to azithromycin.

  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking


These aren't all the side effects of azithromycin. For a full list, see the leaflet inside your medicine packet.



Visit Yellow Card for further information.

6. How to cope with side effects

What to do about:

  • feeling sick (nausea) - stick to simple meals and do not eat rich or spicy food while you're taking this medicine.
  • diarrhoea or being sick (vomiting) - drink lots of fluids such as water or squash to avoid dehydration. Take small, frquent sips if you're being sick. Signs of dehydration include peeing less than usual or having 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.
  • headaches - 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. Do not drive or use tools or machines if you feel dizzy or tired. Do not drink alcohol as it may make you feel worse.
  • changes to your sense of taste - talk with your doctor if this is bothering you.

7. Pregnancy and breastfeeding

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.

For more information about how azithromycin can affect you and your baby during pregnancy, visit the Best Use of Medicines in Pregnancy (BUMPS) website.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

8. Cautions with other medicines

There are some medicines that do not 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.

Important: Medicine safety


9. Common questions

How does azithromycin work?

Azithromycin is from a group of medicines called macrolide antibiotics. Macrolide antibiotics work by killing the bacteria that cause the infection.

How does azithromycin compare with other antibiotics?

There are other macrolide antibiotics that work in the same way as azithromycin. They include erythromycin and clarithromycin.

It's usual to take azithromycin once a day. For erythromycin, it's usually 4 times a day, and twice a day for clarithromycin.

Erythromycin is more likely to cause diarrhoea than either azithromycin or clarithromycin.

All macrolides can be used to treat chest and skin infections. Azithromycin and erythromycin can also be used to treat sexually transmitted infections.

Clarithromycin can also be used to treat Helicobacter pylori, bacteria that can cause stomach ulcers.

Azithromycin and other macrolide antibiotics kill similar types of bacteria to penicillin antibiotics, such as amoxicillin.

Some people are allergic to penicillin antibiotics - they can take macrolides like azithromycin instead.

When will I feel better?


It's very important that you keep taking azithromycin until your course is finished.

Do this even if you feel better. It'll help stop the infection coming back.

What if I don't get better?

Tell your doctor if you don't start feeling better after taking azithromycin for 3 days. Also tell them if, at any time, you start to feel worse.

Can I drink alcohol with it?

Yes, you can drink alcohol with azithromycin.

Will it give me thrush?

Some people get a fungal infection called thrush after taking a course of antibiotics like azithromycin. Antibiotics kill the normal harmless bacteria that help to protect you against thrush.

Symptoms of thrush in the mouth include redness and itching. Women may get vaginal itching.

Ask your doctor or pharmacist for advice if this happens to you.

Will it stop my contraception working?

Azithromycin doesn't stop contraceptive pills, including the combined pill and emergency contraception.

But if azithromycin makes you vomit or have severe diarrhoea (6 to 8 watery poos in 24 hours) for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.


Will it reduce my fertility?

There's no firm evidence to suggest that taking azithromycin will reduce fertility in either men or women.


Is there any food or drink I need to avoid?

You can eat and drink normally while taking azithromycin.

Can I drive or ride a bike?

Azithromycin can cause dizziness. If you're affected by it, do not drive, ride a bike or operate machinery.

Page last reviewed: 6 December 2018
Next review due: 6 December 2021