Clarithromycin

Most adults and children can 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
• have heart problems, including irregular heartbeats (arrhythmia)
• have abnormally low levels of potassium or magnesium in your blood
• have myasthenia gravis – clarithromycin can make your symptoms worse
• have phenylketonuria – some brands of liquid clarithromycin contain the sweetener aspartame, which you should avoid if you have this condition
• are pregnant, trying to get pregnant, or breastfeeding
• have liver or kidney problems

Clarithromycin tablets come in strengths of 250mg or 500mg. 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.

If your doctor prescribes slow-release tablets, the usual dose is 500mg once a day. Sometimes a higher dose of 1g once a day is used in severe infections.

These tablets release the medicine slowly through the day, which means you only usually need to take 1 tablet. If you need 2 slow-release tablets a day and have any questions, talk to your doctor or pharmacist and read the instructions carefully.

How to take it

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

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

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 liquid

Liquid clarithromycin may be made up for you or your child by a pharmacist. Sometimes, you may be given a powder you add water to so you can make the liquid yourself. Follow the instructions in your medicine to do this.

The liquid comes with a plastic syringe or spoon to help you measure the right dose. 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.

Shake the liquid well before use.

Try eating or drinking something straight after taking it, to help avoid any bitter aftertaste.

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

Stick to simple meals and do not eat rich or spicy food. It might help to take your clarithromycin after you've eaten.

If you're being sick, try taking small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat vomiting without speaking to a pharmacist or doctor.

If you take the combined pill or progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.

If you take the combined contraceptive pill or progestogen-only pill and you have severe, watery diarrhoea or any diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Try not to eat foods that cause farting (flatulence) like lentils, beans and onions. Eat smaller meals, eat and drink slowly, and exercise. There are pharmacy medicines that can also help, such as antacids or simeticone. Ask a pharmacist for advice.

Rest and drink plenty of fluids. It's best not to drink too much alcohol. Ask your pharmacist to recommend a painkiller if you need one. Talk to your doctor if your headaches are severe or do not go away.

Avoid having a big meal, smoking, and drinking alcohol, tea or coffee in the evening. Try not to watch television or use your mobile phone before going to bed. Instead, try to relax for an hour before bedtime.

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.

Clarithromycin can be taken while you're pregnant, but other antibiotics may be more suitable. Ask your doctor or pharmacist for advice.

If your baby is healthy, you can take clarithromycin while breastfeeding. Talk to your doctor or pharmacist first.

Clarithromycin passes into breast milk in very small amounts and is unlikely to cause side effects in your baby.

It's important to treat an infection if you're breastfeeding as it could get worse if left untreated.

It's very rare for breastfed babies to have side effects from medicines you're taking. But it's important to keep monitoring your baby if you're taking any medicine while breastfeeding.

Contact your healthcare professional or call 111 as soon as possible if you notice that your baby:

• is not feeding as well as usual or putting on weight as expected
• has an upset stomach such as diarrhoea or being sick (vomiting)
• has a rash
• has oral thrush (a fungal infection in their mouth)
• has changes in their usual sleeping pattern or seems irritable
• seems sweaty

If your baby has any symptoms that are not listed, or if you're worried about them, you can also call 111 or contact any healthcare professional.

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

Check with a pharmacist or your doctor if you're taking any other medicines, including:

• epilepsy medicines, such as carbamazepine or phenytoin
• theophylline for asthma
• colchicine for gout
• digoxin, ivabradine or ranolazine, used for some heart problems
• warfarin or ticagrelor, used to help prevent blood clots (sometimes called a blood thinner)
• a statin medicine to lower your cholesterol, such as simvastatin or atorvastatin
• midazolam, used to treat seizures
• domperidone, used to treat nausea and vomiting

These are not all the medicines that may cause problems if you take them with clarithromycin. For a full list, see the leaflet inside your medicine packet.