Azithromycin is an antibiotic previously recommended for treating chlamydia. Now, doxycycline is the first inline treatment, and azithromycin is only recommended if it isn't suitable for you. Your doctor will make sure you're on the proper treatment.

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Azithromycin is a prescription-only antibiotic that was once used as the main treatment for chlamydia, but is no longer recommended for most people. The recommended treatment for chlamydia is now doxycycline.

Dr Louisa Draper

Medically reviewed by

Dr Louisa Draper

Last reviewed: 17 Aug 2021

How it Works

About Azithromycin

What is azithromycin?

Azithromycin is a prescription only antibiotic that is used to treat many bacterial infections like:

  • chest, throat or nasal infections
  • certain ear infections
  • travellers’ diarrhoea
  • certain sexually transmitted diseases

Azithromycin is a macrolide antibiotic. It is a type of antibiotics that are known as ‘broad spectrum antibiotics’ because they act on many types of bacteria. They are used for the treatment of infections like bronchitis, pneumonia, tonsillitis, sore throat, and sinusitis.

What does azithromycin treat?

Travellers’ diarrhoea

Azithromycin can be used to treat travellers’ diarrhoea. If you catch a tummy bug when travelling, and have 3 or more bouts of loose, watery poo in 24 hours, you may consider antibiotic treatment. This will depend on where you are travelling. The condition is spread mainly through food and water but it can also spread from person to person. It is one of the most common health problems affecting travellers all over the world. Traveller’s diarrhoea can be caused by many different germs like bacteria, viruses and parasites. All these germs are spread through eating and drinking contaminated (dirty) food and water, or using contaminated dishes and cutlery. Travellers' diarrhoea usually gets better in 3 to 5 days. Most cases are mild and do not need treatment. Azithromycin kills the bacteria that may have caused the diarrhoea. If you have a bacterial infection, it will help to stop the symptoms and help to make you feel better more quickly. The dose of azithromycin is a 500mg tablet daily for 3 days. Begin taking azithromycin when you get diarrhoea, not before. It cannot be used as a preventative measure.

Sexually transmitted infections (STIs)

Azithromycin may also be used to treat some sexually transmitted infections (STIs) caused by bacterial infection, like gonorrhoea and syphilis. But it is not the main recommended antibiotic for these infections and would need to be used with specialist advice, and sometimes in a combination with other antibiotics. Antibiotics are not effective against STDs caused by a virus. These are treated with antiviral drugs.

Why is azithromycin no longer used to treat chlamydia?

Azrithromycin was used to treat chlamydia in the past but it is no longer the first recommended option. This is partly because another infection, mycoplasma, which is sometimes present with chlamydia, is becoming resistant to azithromycin. Antibiotic resistance, also called bacterial resistance, happens when germs like bacteria and fungi change and are able to resist the effects of an antibiotic. That means the germs are not killed and continue to grow. Infections caused by antibiotic resistant germs are difficult, and sometimes impossible, to treat. The recommended treatment for most people with chlamydia is now doxycycline. You can order this online from us. If you are pregnant, you must not take doxycycline, and a doctor should recommend the best alternative treatment.

Azithromycin and coronavirus

There have been a number of clinical trials into the effectiveness of azithromycin in treating coronavirus. A study published in the Lancet in March 2021 found little meaningful benefit to the use of azithromycin in coronavirus patients. A study of several independent clinical trials published in Wiley Online Library stated that the use of azithromycin is not recommended and should be discontinued due to the increased risk of bacterial resistance.

How does azithromycin work?

Azithromycin is a type of antibiotic. It works by stopping the bacteria from producing proteins so that it cannot grow and reproduce. The bacteria then die or are destroyed by your body’s natural defences. When used, it will take 7 days for the medicine to cure the chlamydia infection.

How effective is azithromycin?

Azithromycin is no longer recommended as the first choice for the treatment of chlamydia, unless you are pregnant, or cannot tolerate doxycycline treatment.

A 7 day course of the antibiotic doxycycline is now the recommended treatment as it is more effective against both vaginal and rectal chlamydia. Undertreated rectal chlamydia infection may cause the condition to reoccur.

How to take Azithromycin

If you have been given 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.

Do not crumble or break tablets and capsules, swallow them whole with a glass of water or juice. Azithromycin liquid is available for people who find it difficult to swallow tablets.

Be sure to take the medicine exactly as directed by your doctor and always finish the course, even if you begin to feel better before completing the treatment.

Drinking moderate amounts of alcohol will not stop the treatment from working.

Azithromycin side effects

Common side effects

Common side effects of azithromycin that happen in more than 1 in 100 people include:

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

Talk to your doctor or pharmacist if these side effects bother you or do not go away.

Uncommon (serious) side effects

Serious side effects are rare and happen in less than 1 in 1,000 people. Call a doctor straight away if you get:

  • chest pains or a faster or irregular heartbeat
  • yellow skin or if the whites of your eyes turn yellow
  • ringing in your ears or temporary hearing loss
  • vertigo (feeling dizzy and likely to fall over)
  • sharp or severe pain in your back or stomach
  • diarrhoea that contains blood or mucus.

You should also speak to a doctor if you have severe diarrhoea, even without blood or mucus, for more than 4 days. There is a possible serious side-effect called colitis that causes severe and dangerous diarrhoea.

Who can take azithromycin?

Azithromycin can be taken by both children and adults, but 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
  • heart problems, including irregular heartbeats (arrhythmia)
  • liver or kidney problems
  • had diarrhoea when you have taken any antibiotics
  • myasthenia gravis
  • diabetes (the powder form contains sugar)

Some medicines do not work well with azithromycin so your doctor needs to know if you’re taking:

  • antacids for indigestion
  • nelfinavir (medicine for HIV)
  • rifabutin (an antibiotic)
  • ergotamine or dihydroergotamine for migraine
  • warfarin to thin blood or prevent blood clots
  • ciclosporin or tacrolimus
  • colchicine for gout
  • digoxin for some heart problems
  • any medicines for an irregular heartbeat (arrhythmia), such as amiodarone or sotalol.

Azithromycin can sometimes affect your heartbeat, so it is important not to take it with other medicines that have the same side effect. It's important that you tell your doctor if you're taking other medicines that can affect your heartbeat. These can include:

  • antidepressants such as citalopram
  • antipsychotics
  • some anti sickness medicines such as domperidone
  • some antibiotics, like moxifloxacin

Read the leaflets that come with your medicines as they have important information but do talk to your doctor or a pharmacist if you have any worries or concerns.

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