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What does it do?

Mesalazine is used to treat and prevent inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease.

Before you start

  • Tell your doctor if you have liver or kidney problems.
  • Tell your doctor if you have asthma, or have had problems with aspirin.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
  • Mesalazine can affect fertility in men. Discuss this with your doctor.
  • Mesalazine enema contains metabisulfites. Tell your doctor if you have an allergy to sulfites.

How should you take it?

Take mesalazine regularly as directed.
Take the tablets with a large glass of water. Do not crush or chew.
Empty the granule sachet onto your tongue and then drink a glass of water. Do not crush or chew the granules.
Remove the wrapper before inserting the suppositories into the rectum.
Shake the enema container well before use. Insert the contents of the enema into the rectum and retain for as long as possible.

What if you forget a dose?

Take the missed dose as soon as possible. If it is close to the time for your next dose, skip the missed dose and carry on as normal. Do not take two doses at the same time.

Can you take other medicines?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Reduced number of blood cells that fight infections or help your blood to clot - symptoms include: fever, chills, sore throat or generally feeling unwell, or easy or unusual bruising or bleeding

Symptoms of allergy including: skin rash, itching, swelling, trouble breathing

Chest pain

Severe stomach pain, nausea

Symptoms of liver problems including: yellow skin or eyes, itching, dark urine, pale bowel motions, abdominal pain

Tell your doctor immediately

Diarrhoea, stomach upset

Tell your doctor


Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • You may not notice the effects of mesalazine straight away – it can take several weeks before you start to feel better.
  • You will need regular blood tests while taking mesalazine to check if it is causing problems with your liver, kidneys or blood.
  • This medicine is also known as 5-ASA.

This leaflet contains important, but not all, information about this medicine.

Prepared by the MyMedicines Committee at Christchurch Hospital, Te Whatu Ora - Waitaha, New Zealand. March 2023

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

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About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at Te Whatu Ora – Waitaha. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed