A macrolide antibiotic · Written by the Lyng Pharmacy team, based on NHS and BNF guidance · Updated August 2026
Also sold asKlaricid
Type of medicineMacrolide antibiotic
Available asTablets, oral suspension, granules
How you get itPrescription only
Clarithromycin is commonly the antibiotic of choice when someone cannot have penicillin. It works well, but it interacts with more medicines than most antibiotics — statins in particular — so it is worth a proper check before you start it.
What it is used for
Chest infections, ear, throat and sinus infections, some skin and soft tissue infections, and as part of the treatment for Helicobacter pylori in the stomach.
It is frequently chosen for people with penicillin allergy.
How to take it
Usually twice daily, with or without food — though taking it with food reduces the nausea and stomach upset it commonly causes. Space doses about twelve hours apart.
Suspension should be shaken well and measured with the syringe or spoon provided.
Finish the whole course even if you feel better after a couple of days, unless a healthcare professional advises otherwise.
Interactions — check before you start
Tell your prescriber and pharmacist everything you take. Clarithromycin significantly raises the level of several medicines, and some combinations are avoided altogether.
Statins — simvastatin and atorvastatin are usually paused for the course, because the combination raises the risk of serious muscle problems
Warfarin — the INR usually needs rechecking
Some heart rhythm medicines, and other medicines that affect the QT interval
Nausea, vomiting, diarrhoea, stomach ache and a metallic or bitter taste are the common ones. Taking it with food helps. The taste change resolves after the course.
Get medical advice for:
Severe, watery or bloody diarrhoea during or after the course
Palpitations, fainting or an irregular heartbeat
Yellowing of the eyes or skin
A widespread rash, blistering or peeling skin, or swelling of the face or throat — call 999 for breathing difficulty
Tell your prescriber if you are pregnant or breastfeeding, as an alternative may be preferred.
Always read the label. This page is general information, not advice for your situation. Doses, warnings and interactions differ between products and between people. Check the leaflet inside your medicine, and ask our pharmacist if anything is unclear — that conversation is free and takes two minutes.
Questions about Clarithromycin?
1 Lyng Lane, West Bromwich B70 7RW · Mon–Fri 8:30am–6pm, Sat 9am–1pm · 0121 500 5756
Why do I have to stop my statin while taking clarithromycin?
Clarithromycin raises statin levels substantially, increasing the risk of serious muscle problems. Simvastatin and atorvastatin are usually paused for the course and restarted afterwards.
Should I take clarithromycin with food?
It can be taken either way, but food reduces the nausea and stomach upset it commonly causes.
Is clarithromycin safe if I am allergic to penicillin?
It is a different class of antibiotic and is frequently chosen for people with penicillin allergy.
Why does clarithromycin give me a metallic taste?
It is a common and harmless effect that resolves once the course finishes.
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