Clarithromycin

What is clarithromycin?

Clarithromycin is a macrolide antibiotic used to treat various bacterial infections[1].  

What is clarithromycin used for?

Clarithromycin is commonly used to treat[1]: 

• Respiratory tract infections (e.g., bronchitis, pneumonia) 

• Skin infections 

• Ear infections 

• Stomach ulcers caused by Helicobacter pylori (in combination with other medications) 

How does clarithromycin work?

Clarithromycin is known as ‘bacteriostatic’ and works by preventing protein synthesis stopping their growth and helping to kill the bacteria. It is not effective against viral infections like the common cold or flu[1]. 

Who can take clarithromycin?

Clarithromycin can be taken by most adults and children[1]. 

Clarithromycin may not be suitable for:  

• If you have had an allergic reaction to clarithromycin or the ingredients listed as part of your medicine 

• People with liver or kidney disease (may need a lower dose) 

• Those with heart rhythm disorders (e.g., long QT syndrome) 

• If you are pregnant, trying to get pregnant or breastfeeding  

Always consult a doctor or pharmacist before starting clarithromycin, and follow the instructions in the Patient Information Leaflet[2].

How do you take clarithromycin?

Clarithromycin comes as tablets, modified release tablets, granules or as an oral suspension. It can be taken with or without food. Swallow the tablets whole with a glass or water, do not crush or chew the modified-release forms. The granules should be poured into water before being consumed. Clarithromycin oral suspension needs to be shaken well before use. It should come with a syringe or spoon designed to hold the correct amount. If you do not have either, ask your pharmacist to supply a spare rather than using a kitchen teaspoon[1]. 

What is the typical dosage for clarithromycin?

The dose of clarithromycin depends on the condition being treated[1]: 

• Typical adult dose: 250–500 mg twice a day 

• Modified-release tablets: usually taken once daily 

• Children: dose is weight-based and often given as a liquid suspension 

Always follow your doctor’s or pharmacist’s instructions precisely and take your medicine at the same time every day, spacing doses out evenly throughout the day when applicable. 

Can you stop taking clarithromycin early?

No, it is important that you carry on taking the medicine until the course is finished even if you feel better[1]. If you stop early, your infection could come back and can lead to bacterial resistance.  

What do you do if you take too much clarithromycin?

Taking an extra dose of clarithromycin is unlikely to harm you, but you may experience an increased risk of side effects like nausea, vomiting, diarrhoea and abdominal pain[1]. 

Talk to your doctor or pharmacist if you are worried or take more than 1 extra dose[1]. 

What if you forget a dose of clarithromycin?

If you miss a dose, take it as soon as you remember. If it's almost time for your next dose, skip the missed dose and continue with your regular schedule. Never take 2 doses at the same time. 

What are the side effects of clarithromycin?

The most common side effects of clarithromycin are[1]: 

• Nausea and vomiting 

• Diarrhoea 

• Gastrointestinal discomfort 

• Altered taste 

• Headaches 

The most serious side effects of clarithromycin are rare, but can include[1]: 

• Liver problems (yellowing of skin/eyes) 

• Severe allergic reactions (e.g. rash, itching, swelling) 

• Irregular heartbeat 

• Hearing loss (rare and usually reversible) 

If you are experiencing any of these more serious side effects, consult your doctor or visit A&E immediately.  

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice.

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Medicines you can't take with clarithromycin

Inform your doctor or pharmacist before starting clarithromycin if you are taking the following medicines[1]: 

• Statins like simvastatin (can increase exposure to statin and their side effects) 

• Ergotamine (used for migraines) 

• Digoxin (increases concentration of digoxin) 

• Colchicine (especially if you have kidney/liver issues; increase exposure to colchicine) 

• Medicines for epilepsy such as carbamazepine (increases concentration of carbamazepine) 

• Midazolam (increased exposure to midazolam) 

• Warfarin (can increase the anticoagulant effect) 

• Insulin (increased risk of hypoglycaemia) 

Please note that this is not a complete list of drug interactions, clarithromycin interacts with many medicines therefore it is important to always tell your doctor or pharmacist about any medication you’re taking before starting a new medicine, and follow the directions provided[2]. 

Frequently asked questions about clarithromycin

Can I drink alcohol while taking clarithromycin? 

Yes, you can drink alcohol with clarithromycin, but it can increase the risk of side effects like stomach upset and dizziness[1]. 

Can clarithromycin cause yeast infections? 

Yes, like many antibiotics, it can also kill the normal harmless bacteria which can lead to opportunistic infections like thrush. Speak to your pharmacist or doctor for advice[1]. 

Is it safe during pregnancy? 

Only if the benefit of taking it outweighs the risk. It is best to discuss with your doctor or pharmacist[1]. 

Can I take it with food? 

Yes, Clarithromycin can be taken with or without food[1].

For the official NHS guide to clarithromycin, visit their website.