Experiences with
Clarithromycin

Clarithromycin is an antibiotic. It's used to treat chest infections such as pneumonia, skin problems such as cellulitis, and ear infections. It's also used to treat Helicobacter pylori, a bacteria that can cause stomach ulcers.

Clarithromycin is sometimes used by people who have an allergy to penicillin and antibiotics similar to penicillin, like amoxicillin.

Clarithromycin is only available on prescription.

It comes as tablets, granules, or a liquid that you drink. It can also be given by injection, but this is usually only done in hospital.

Who can take clarithromycin

Clarithromycin can be taken by most adults and children.

Who may not be able to take clarithromycin

Clarithromycin is not suitable for some people. To make sure it's safe for you, tell your doctor if you:

have ever had an allergic reaction to clarithromycin or any other medicine
have ever had diarrhoea when you have taken antibiotics before
have a fast, pounding or irregular heartbeat
have abnormally low levels of potassium or magnesium in your blood
have myasthenia gravis – clarithromycin can make the symptoms of this muscle-weakening condition worse
have an illness called phenylketonuria – people with phenylketonuria have to avoid a sweetener called aspartame (this can be found in some sweeteners you may put in your drinks or food). Some brands of liquid clarithromycin contain aspartame
are pregnant, trying to get pregnant, or breastfeeding.

Dosage

Clarithromycin tablets come in 250mg or 500mg strengths. The granules come in 125mg or 250mg sachets. The liquid comes in strengths of 125mg in 5ml or 250mg in 5ml.

The usual dose of clarithromycin is 250mg to 500mg twice a day, although the dose may be lower for children or if you have kidney problems.

If your doctor prescribes slow-release tablets, the usual dose is 500mg once a day. Sometimes the dose is higher for more severe infections. These tablets release the medicine slowly, which means that 1 dose a day is enough.

Try to take your medicine at the same time every day.

Clarithromycin comes in different forms and strengths, and there are different ways to take it:

How to take tablets

Swallow the tablets whole with a drink of water. Do not chew or break them.

You can take them with or without food.

How to take granules

Open the pack (or packets) and mix the granules with a small amount of water to drink.

The granules can be used for children or people who find it difficult to swallow tablets.

How to take liquid

The liquid can be used for children or people who find it difficult to swallow tablets.

If you or your child are taking clarithromycin liquid, your pharmacist will usually make it up for you.

The medicine will come with a plastic syringe or spoon to help you take the right amount. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.

How long to take it for

For skin problems such as cellulitis, you may have to take the medicine for about 7 days before you see any improvement.

If you have a Helicobacter pylori infection, even if the bacteria are no longer in your stomach, it can take some time before you feel better.

Your doctor will usually give you a medicine to reduce stomach acid, such as omeprazole or lansoprazole, while the ulcer heals. You should start feeling better when you finish the treatment to reduce your stomach acid.

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

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

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

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

If you take too much

Taking an extra dose of clarithromycin is unlikely to harm you or your child. However, it may give you temporary side effects, like stomach pain, feeling and being sick (nausea and vomiting), and diarrhoea.

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

Common side effects

These common side effects of clarithromycin happen in more than 1 in 100 people. There are things you can do to help cope with them:

If this advice does not help and any of these side effects continue to bother you, keep taking the medicine, but tell your doctor or pharmacist.

Serious side effects

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

Call a doctor or contact 111 straight away if you get:

a faster or irregular heartbeat
pale poo, dark pee and a yellow colour to the whites of your eyes or skin (although this may be less obvious on brown or black skin) – these can be signs of liver problems
severe pain in your stomach and/or back – this can be a sign 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, also speak to a doctor
hallucinations (seeing or hearing things that are not there)

Go to 111.nhs.uk or call 111.

Serious allergic reaction

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

These are not all the side effects of clarithromycin. For a full list, see the leaflet inside your medicine packet.

Clarithromycin and pregnancy

Clarithromycin can be taken in pregnancy or while breastfeeding, however other antibiotics may be more suitable. Discuss this with your doctor.

Clarithromycin and breastfeeding

If your doctor or health visitor says your baby is healthy, you can take clarithromycin while breastfeeding.

Clarithromycin passes into breast milk in very small amounts, and is unlikely to cause side effects in your baby. However, some babies have had mild upset stomach and drowsiness.

If your baby is not feeding as well as usual, has a rash, is unusually sleepy, has an upset stomach or oral thrush (a fungal infection in their mouth), or if you have any other concerns about your baby, talk to your doctor, pharmacist, health visitor or midwife.

Clarithromycin and fertility

There's no evidence to suggest that taking clarithromycin reduces fertility in either men or women.

Cautions with other medicines

There are some medicines that do not mix well with clarithromycin.

Tell your doctor if you're taking any of these medicines before you start clarithromycin:

ergotamine or dihydroergotamine, used to treat migraines
medicines for epilepsy, such as carbamazepine or phenytoin
theophylline for asthma
colchicine for gout
digoxin, for some heart problems
warfarin, used to help prevent blood clots (sometimes called a blood thinner)
a statin medicine to lower your cholesterol, such as simvastatin or atorvastatin

Mixing clarithromycin with herbal remedies and supplements

Clarithromycin may not mix well with some complementary and herbal remedies.

It's best to check with your doctor or a pharmacist before taking any herbal remedies or supplements while taking clarithromycin.

There's not enough information to say that complementary medicines and herbal remedies are safe to take with clarithromycin. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.