Clarithromycin for infection

Clarithromycin is a macrolide antibiotic. It can be taken by people who are allergic to penicillin.

It is important to complete the prescribed course (unless you are told to stop). Otherwise your infection could come back.

Any side-effects are usually mild. The most common are diarrhoea, feeling sick, abdominal discomfort, and unusual tastes.

Type of medicine A macrolide antibiotic
Used for Bacterial infections including chest, skin, and ear infections
Some types of stomach ulcers
Also called Clarie XL®; Febzin XL®; Klaricid®; Klaricid XL®; Mycifor XL®
Available as Tablets, oral liquid medicine, sachet, and modified-release tablets

Clarithromycin is prescribed to treat bacterial infections such as respiratory infections, ear infections and skin infections. It can be taken by adults and children. It works by stopping the bacteria causing the infection from multiplying.

Clarithromycin is also given to get rid of Helicobacter pylori. This is the bacterium believed to cause stomach ulcers. If you are prescribed it for this reason, you will also be prescribed other medicines to take alongside it.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking clarithromycin it is important that your doctor knows:

  • If you are pregnant or breast-feeding.
  • If you have any problems with the way your liver works or the way your kidneys work.
  • If you know you have an unusual heart rhythm.
  • If you have a muscle disorder called myasthenia gravis.
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start taking the antibiotic, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about clarithromycin and provide a full list of the side-effects which you may experience from taking it.
  • Take clarithromycin exactly as your doctor tells you to. Most forms of clarithromycin are taken twice a day, in the morning and evening. If you are given a modified-release tablet (these have an XL after the brand name - for, example Klaricid XL®, Clarie XL®, Mycifor XL®), you will only need to take one dose a day, as the medicine inside these tablets is released slowly over the day.
  • Standard-release tablets, liquid medicine, and sachets can all be taken either before or after food. Modified-release tablets (these are the ones that are only taken once daily) should be taken after food. Do not chew or break modified-release tablets, as this will affect the way the medicine inside them is released.
  • When clarithromycin is prescribed for a child, the dose will depend upon the child's weight. Make sure you read the label carefully so that you measure out the correct amount of medicine.
  • If you have been given clarithromycin sachets to take, open the sachet and mix the granules into a small glass of water before taking.
  • If you forget to take a dose, take one as soon as you remember. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a forgotten one.
  • It is usual for a course of treatment to last for 5-14 days. Even if you feel your infection has cleared up, keep taking the antibiotic until the course is finished (unless your doctor tells you otherwise). This is to prevent the infection from coming back and being more difficult to treat.
  • Some people develop thrush (redness and itchiness in the mouth or vagina) after taking a course of antibiotics. If this happens to you, speak with your doctor or pharmacist for advice about how to treat it.
  • This antibiotic may stop the oral typhoid vaccine from working. If you are having any vaccinations, make sure the person treating you knows that you are taking this medicine.
  • If you are having an operation or dental treatment, tell the person carrying out the treatment that you are taking clarithromycin.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with this antibiotic.
  • If you still feel unwell after completing your course of the antibiotic, make another appointment to see your doctor.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with clarithromycin. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common clarithromycin side-effects (these affect less than 1 in 10 people) What can I do if I experience this?
Feeling or being sick, stomach ache, wind, indigestion Stick to simple meals - avoid rich or spicy food
Diarrhoea Drink plenty of water to replace lost fluids. If the diarrhoea continues or is severe, speak with your doctor as soon as possible
Tooth or tongue discolouration, and changes in the way things taste or smell This will disappear after you finish your treatment
Sore mouth Speak with your doctor if this becomes a problem
Headache Ask your pharmacist to recommend a suitable painkiller

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • If you have been given liquid medicine, it will have been made up by the pharmacy and it lasts for a limited number of days only. Check the expiry date on the bottle and do not use it after this date.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • British National Formulary; 67th Edition (March 2014) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
3421 (v25)
Last Checked:
24/04/2014
Next Review:
23/04/2017
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