About clarithromycin - NHS Skip to main content

About clarithromycin

Clarithromycin is an antibiotic medicine.

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 from a group of medicines called macrolide antibiotics. Macrolide antibiotics work by stopping the growth of bacteria that cause the infection.

Clarithromycin is only available on prescription.

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

Key facts

  • You'll usually take clarithromycin twice a day, once in the morning and once in the evening.
  • Some people take slow-release clarithromycin tablets. This means that the medicine is gradually released into your body over 24 hours. These are taken once a day.
  • For most infections, you should feel better within a few days, but it's important to finish your full course of medicine.
  • Common side effects include feeling or being sick, stomach cramps, and diarrhoea.

Page last reviewed: 25 March 2026
Next review due: 25 March 2029