Antibiotics, macrolide

Page last reviewed: 13/07/2011

Antibiotics are medicines that kill bacteria that cause infection. Antibiotics don't work against diseases caused by viruses.

Macrolide antibiotics are a particular type of antibiotic used to treat, and sometimes prevent, a wide variety of bacterial infections (see Macrolide antibiotics - uses for more information).

How they work

Macrolide antibiotics stop bacteria multiplying by preventing them from being able to produce proteins that are essential for their growth. The bacteria eventually die or are killed by your immune system.


Macrolide antibiotics are:

  • azithromycin (brand name Zithromax),
  • clarithromycin (brand names Klacid and Klacid LA),
  • erythromycin (brand names Erymax, Erythrocin, Erythroped and Erythroped A),
  • spiramycin (no brand), and
  • telithromycin (brand name Ketek).

Finishing the course

It is essential that you finish taking your course of antibiotics even if you feel better, unless your GP tells you otherwise.

If you stop taking an antibiotic part way through a course, the bacteria can become resistant to the antibiotic. The infection could then be harder to treat in future (see Frequently asked questions for more information).

Using Antibiotics properly

It's very important that people take antibiotics properly, and only when they are needed. For example, colds and flu are caused by viruses, so there is no point taking an antibiotic for colds, the flu and most coughs. Read our Action on Antibiotics section to learn more about this.


Page last reviewed: 13/07/2011


Macrolide antibiotics are only effective in treating bacterial infections associated with the following conditions:

  • Ear, nose and throat infections - such as otitis media (infection of the middle ear), labyrinthitis (infection of the inner ear), sinusitis (infection of the sinuses), tonsillitis (infection of the tonsils) and laryngitis (infection of the voice box).
  • Chest infections - such as pneumonia (infection of the lining of the lung), bronchitis (infection of the airways of the lung) and whooping cough.
  • Skin infections - such as eczema, psoriasis or acne that has become infected.
  • Mouth and dental infections - such as gingivitis (infection of the gums) and a tooth abscess (infection in the root of a tooth).
  • Sexually transmitted infections - such as chlamydia.


Macrolide antibiotics may also be prescribed to prevent certain types of bacterial infection.

For example, if you have sickle-cell disease, or have had your spleen removed (splenectomy), you may need to regularly use antibiotics to prevent infections.

Also, if you have undergone any type of dental procedure and are at risk of endocarditis (infection of the heart lining and valves), you may need to take a course of antibiotics. Speak to your dentist and GP before any procedure for further advice.

Alternative to penicillin

Macrolide antibiotics can also be used as an alternative to penicillin antibiotics. They are often prescribed for people who are allergic to penicillin.

Page last reviewed: 13/07/2011

When to avoid them

Macrolide antibiotics should be avoided if you have had a previous allergic reaction to them.

They should also be avoided if you have:

  • an inherited blood disorder, such as porphyria, or
  • a heart rhythm disorder (or you are at risk of developing a heart rhythm disorder).

You should not take telithromycin if you have myasthenia gravis.

Using them with caution

Macrolide antibiotics should be used with caution if you have a kidney or liver problem. Ask your GP or pharmacist for more information.

Pregnancy and breastfeeding

If you are pregnant or are breastfeeding, the only type of macrolide antibiotic you can take is erythromycin (Erymax, Erythrocin, Erythroped, or Erythroped A).

Erythromycin can be used at the usual doses throughout your pregnancy, or while you are breastfeeding.

Other macrolide antibiotics should only be used during pregnancy and when breastfeeding if there is no other suitable alternative.

Page last reviewed: 13/07/2011

Some of the general side effects of macrolide antibiotics are given below. For more specific information on side effects for a particular antibiotic,

Common side effects

Up to one in 10 people may experience the following:

  • pain in the stomach or intestines,
  • diarrhoea,
  • nausea, and
  • vomiting.

Speak with your GP if you begin to experience any of these side effects. If your side effects become severe, it may be possible for you to take a smaller dose to avoid them.

These side effects are less severe if you are taking azithromycin (Zithromax) or clarithromycin (Klacid or Klacid LA).

Less common side effects

Up to one in 100 people may experience the following:

  • dizziness,
  • stomach irritation,
  • indigestion (dyspepsia), and
  • skin rash.

Rare and very rare side effects

Between one in 1,000 and one in 10,000 people may experience the following:

  • jaundice,
  • heart arrhythmias (disorders that affect the way the heart beats),
  • Stevens-Johnson syndrome (a very severe allergic reaction), and
  • tinnitus - this usually disappears once you stop taking the macrolide antibiotics.

Ability to drive

Macrolide antibiotics do not affect your ability to drive.

However, on very rare occasions you may experience some dizziness. If this occurs, do not attempt to drive. Speak to your GP for further advice.

Page last reviewed: 13/07/2011

When two or more medicines are taken at the same time, the effects of one of the medicines can be altered by the other. This is known as a drug-drug interaction.

If you want to check that your medicines are safe to take with a macrolide antibiotic, speak to your GP or pharmacist. You should also read the patient information leaflet that comes with your medicine.

Combined oral contraceptive pill

There is a small risk that macrolide antibiotics can reduce the effectiveness of the combined oral contraceptive pill.

Women taking combined oral contraceptives should use an extra method of contraception, such as condoms, while taking a short course of macrolide antibiotics and for seven days after finishing the antibiotics.

Interactions with food and alcohol

There are no known interactions between macrolide antibiotics and food.

However, marolide antibiotics can cause stomach irritation, so try to take them with (or just after) food or milk. This reduces the likelihood of this side effect.

There are no known interactions between macrolide antibiotics and alcohol.

Page last reviewed: 13/07/2011

Take macrolide antibiotics as directed on the packet or patient information leaflet, or as directed by your GP or pharmacist.

Missed dose

If you forget to take your dose of macrolide antibiotic, take that dose as soon as you remember and then continue to take your course of antibiotics as normal.

However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

If you have to take two doses closer together than normal, there is an increased risk of side effects.

Accidentally take one extra dose

Accidentally taking one extra dose of your macrolide antibiotic is unlikely to cause you any serious harm. However, it will increase your chances of experiencing gastrointestinal side effects such as pain in your stomach, diarrhoea, nausea and vomiting.

Accidentally take more than one extra dose

If you accidentally take more than one extra dose of your macrolide antibiotic, contact your GP

Page last reviewed: 13/07/2011

Why should antibiotics not be used to treat coughs and colds?

All colds and most coughs and sore throats are caused by viruses. Antibiotics do not work against viral infections.

How should I treat my cold?

The best way to treat most colds, coughs or sore throats is to drink plenty of fluids and rest. Colds can last about two weeks and may end with a cough and bringing up phlegm. There are many over-the-counter remedies to ease the symptoms - paracetamol, for example. Ask your pharmacist for advice. If the cold lasts more than three weeks, or you become breathless or have chest pains, or already have a chest complaint, see your doctor.

But what about my children? They're always getting coughs and colds.

It is common for children to get coughs and colds, especially when they go to school and mix with other children. Ask your pharmacist for advice. If the symptoms persist and you are concerned, see your doctor - but you should not expect to be prescribed antibiotics.

What is antibiotic resistance?

Bacteria can adapt and find ways to survive the effects of an antibiotic. They become 'antibiotic resistant' so that the antibiotic no longer works. The more we use an antibiotic, the more likely it is that bacteria will become resistant to it. Some bacteria that cause infections in hospitals, such as MRSA, are resistant to several antibiotics.

Why can't other antibiotics be used instead?

They can, but they may not be as effective and they may have more side effects. And eventually, the bacteria will become resistant to them too. We cannot be sure we will always be able to find new antibiotics to replace the old ones. In recent years, fewer and fewer new antibiotics have been discovered.

How can antibiotic resistance be avoided?

By using antibiotics carefully, we can slow down the development of resistance. It is not possible to stop it completely, but slowing it down stops resistance spreading and buys some time to develop new types of antibiotics.

What can I do about antibiotic resistance?

You should only use antibiotics when it is appropriate to do so. We now know that most coughs and colds get better just as quickly without antibiotics.

When antibiotics are prescribed, the complete course should be taken to get rid of the bacteria completely. If the course is not completed, some bacteria may be left to develop resistance.

So when will I be prescribed antibiotics?

Your doctor will only prescribe antibiotics when you need them; for example, for a kidney infection or pneumonia. Antibiotics may be life-saving for infections such as meningitis. By only using them when necessary, they are more likely to work when we need them in future.

Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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