What are the side effects of clarithromycin?

It is important to tell your health professional about any medicines you may be taking, or if you have any current illness, allergies or long-term health conditions. This will help them decide if clarithromycin is suitable for you.

Side effects of clarithromycin

(1 to 10 in 100 people)
(fewer than 1 in 100 people)
(fewer than 1 in 1000 people at high doses)
Stomach pain and cramps
Affected ability to taste
Thrush (candida infection)
Rash Severe allergic reactions
Infection with other bacteria (Clostridium difficile-associated disease)
Ear problems (dizziness, hearing loss, ringing in the ears [tinnitus])
Liver abnormalities (cholestatic hepatitis)
Lower numbers of platelets in the blood (thrombocytopenia, lowered clotting ability)
Inflammation of the pancreas (pancreatitis)
Slowed heart rate
Note: this is not a complete list of all the possible side effects of clarithromycin.

Heart problems

Clarithromycin can affect your heart rate, so you must tell your doctor if you have any heart problems (e.g. irregular heart beat or arrhythmia).

Liver problems

Clarithromycin can cause a liver problem called cholestatic hepatitis, but this is rare (fewer than 1 in 1000 people will experience the side effect). This affects how your liver works, but it is reversible. It can start while you are taking clarithromycin, or a few weeks after you have stopped taking it, and can last for 5 to 6 weeks. The risk of cholestatic hepatitis increases if you are 55 years or older, male, and if you take clarithromycin for more than 14 days.

Antibiotics and allergic reactions

Some people experience an allergic reaction to clarithromycin or other antibiotics. This is due to an over-reaction of their immune system to the antibiotic.

Symptoms of an allergic reaction can include:

  • hives (large, red raised areas on the skin)
  • swollen lips, tongue or mouth
  • fever (a temperature of 38.5°C or higher)
  • breathing problems
  • fainting.

Seek medical advice if you experience any of these symptoms while you are taking an antibiotic.

It is not known why this happens to some people and not others, but it may mean that you will have to avoid taking clarithromycin in the future. There are other types of antibiotics which don’t cause this reaction that will be suitable for you.

Read more about the common side effects of antibiotics.

Who can I ask about side effects?

If you’re concerned that you or someone in your care may have had side effects related to a medicine, seek medical advice. People with questions about their medicines or seeking general information about side effects can also call the NPS Medicines Line on 1300 633 424 (Monday-Friday, 9am-5pm AEST). To report possible side effects call the Adverse Medicine Events (AME) line on 1300 134 237 from anywhere in Australia (Monday–Friday, 9am–5pm AEST).

  • Rossi S, ed. Australian Medicines Handbook [online]. Adelaide: AMH, July 2012.
  • Sweetman S, ed. Martindale: The complete drug reference [online]. London: Pharmaceutical Press (accessed 18 October 2011).
  • Antibiotic Expert Group. Therapeutic Guidelines: Antibiotic version 14; Clarithromycin. Melbourne: Therapeutic Guidelines Limited, 2012 (accessed 27 March 2012).