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Clozapine

Safety advisory - constipation: a potentially serious side effect

22 April 2022

Product Information (PI) and Consumer Medicine Information (CMI) for clozapine have been updated to strengthen warnings about potential severe gastrointestinal side effects, including constipation.

Clozapine is used to treat schizophrenia when other antipsychotic medicines either have not worked or have caused severe side effects. In Australia it is known by the brand names Clozaril, Clopine and others.

Clozapine may also affect the bowels by slowing them down and can cause severe constipation. This condition is known as clozapine-induced gastrointestinal hypomotility. If untreated, it can lead to serious problems.

We are reminding consumers who take clozapine to look out for changes in their bowel function, and to contact their health professional if they develop any of the symptoms listed in the ‘Information for consumers' section below.

Information for consumers

If you or someone you provide care for is taking clozapine, you should contact a health professional immediately if constipation develops or there are any signs that bowel activity is slowing down, such as:

  • no bowel movements, bowel movements less often than usual, or difficulty passing a stool
  • nausea and/or vomiting
  • bloating, tenderness or swelling of the abdomen
  • stomach pains or spasms.

More information is available in the CMI for clozapine.

If you have any questions or concerns about this issue, talk to your health professional.

Information for health professionals

The PI for clozapine has been updated to reinforce and expand on existing warnings that severe gastrointestinal adverse reactions have occurred with its use. Gastrointestinal hypomotility induced by clozapine may lead to hospitalisation, surgery and death.

The warnings emphasise screening patients for constipation before starting and during treatment with clozapine, followed by treatment according to current clinical guidelines if necessary.

Read the Medicines Safety Update for more detailed information.

Reporting problems

Consumers and health professionals are encouraged to report problems with medicines or vaccines. Your report will contribute to the TGA's monitoring of these products.

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medicine or vaccine.