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Generic name: mesalamine

What is Canasa?

Canasa is a prescription medicine used to treat adults with active ulcerative proctitis (ulcerative rectal colitis).
It is not known if Canasa is safe and effective in children.

Who should not use Canasa?

Do not use Canasa if you are:

  • allergic to medicines that contain salicylates, including aspirin.
  • allergic to mesalamine or any of the ingredients in Canasa. See the end of this Patient Information guide for a complete list of ingredients in Canasa.

Ask your doctor if you are not sure if your medicine is listed above.

What should I tell my healthcare provider before using Canasa?

Before using Canasa, tell your doctor if you have any medical conditions, including if you:

  • have a history of allergic reaction to the medicine sulfasalazine (Azulfidine).
  • have kidney problems.
  • have ever had inflammation of the sac around your heart (pericarditis).
  • have liver problems.
  • are pregnant or plan to become pregnant. It is not known if Canasa can harm your unborn baby.
  • are breastfeeding or plan to breastfeed. Canasa can pass into your breast milk. Talk to your doctor about the best way to feed your baby if you use Canasa.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements.
Using Canasa with certain other medicines may affect each other. Using Canasa with other medicines can cause serious side effects.
Especially tell your doctor if you take nonsteroidal anti-inflammatory drugs (NSAIDS), or medicines that contain azathioprine or 6-mercaptopurine. Taking Canasa with NSAIDS may cause kidney problems. Taking Canasa with azathioprine or 6-mercaptopurine may cause blood problems. Ask your doctor if you are not sure if you are taking one of these medicines.
Your doctor may do certain tests during treatment with Canasa.
Know the medicines you take. Keep a list of them to show your doctor and pharmacist when you get a new medicine.

How should I use Canasa?

  • Use Canasa exactly as prescribed by your doctor. Your doctor will tell you how long to continue using Canasa.
  • Canasa comes as a suppository that you insert into your rectum.
  • Do not cut or break the suppository.
  • Use Canasa 1 time each day at bedtime, for 3 to 6 weeks. It is not known if Canasa is safe and effective for use for longer than 6 weeks.
  • After you insert Canasa in your rectum, try to keep (retain) the suppository in your rectum for 1 to 3 hours or longer if possible.
  • It is important for you to stay well hydrated during treatment with Canasa. Be sure to drink plenty of fluids while taking Canasa.
  • If you miss a dose of Canasa, insert it as soon as you remember. If it is almost time for your next dose, skip the missed dose. Insert the next dose at your regular time. Do not insert 2 doses at the same time.
  • Canasa can stain surfaces including clothing and other fabrics, flooring, painted surfaces, marble, granite, vinyl and enamel. Keep Canasa away from these surfaces to prevent staining.

What are the possible side effects of Canasa?

Canasa may cause serious side effects, including:

  • kidney problems. Your doctor will do certain tests before you start using Canasa and during your treatment with Canasa.
  • acute intolerance syndrome and other allergic reactions. Some people who use Canasa can have allergic type reactions, including Acute Intolerance Syndrome. Other allergic reactions can cause heart problems including an inflammation of the sac around the heart (pericarditis), blood problems, and problems with other organs in the body including the kidneys, liver and lungs. These problems usually happen in people who have had an allergic reaction to medicines containing sulfasalazine. Stop using Canasa and tell your doctor right away if you get any of these symptoms:
    • cramps
    • fever
    • stomach (abdominal) pain
    • headache
    • bloody diarrhea
    • rash
    • chest pain
    • shortness of breath
    • decrease in the amount of urine
    • fatigue
    • eye inflammation
  • liver problems. This can happen in people who have a history of liver problems and have taken other medicines that contain mesalamine. Tell your doctor right away if you get any of these symptoms while using Canasa:
    • yellowing of your eyes
    • flu-like symptoms
    • itchy skin
    • nausea or vomiting
    • feeling very tired
  • sun sensitivity. Canasa can make your skin sensitive to the sun if you have skin conditions such as atopic dermatitis and atopic eczema. Try to limit your time in the sun. You should use sunscreen and wear a hat and clothes that cover your skin if you have to be in the sunlight.
  • kidney stones. Drink plenty of fluids when using Canasa to decrease your chance of getting kidney stones. Call your doctor right away if you get any of these symptoms:
    • severe pain in your side
    • severe pain in your back
    • blood in your urine

The most common side effects of Canasa include:

  • dizziness
  • rectal pain
  • acne
  • fever
  • inflammation of the large intestine (colitis)
  • rash

These are not all of the possible side effects of Canasa.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

General information about the safe and effective use of Canasa

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information guide. Do not use Canasa for a condition for which it was not prescribed. Do not give Canasa to other people, even if they have the same symptoms that you have. It may harm them.
You can ask your doctor or pharmacist for information about Canasa that is written for health professionals.

How should I store Canasa?

  • Store Canasa at room temperature between 68°F to 77°F (20°C to 25°C).
  • Canasa may be refrigerated.
  • Keep Canasa away from direct heat, light, or humidity.

Keep Canasa and all medicines out of the reach of children.

What are the ingredients in Canasa?

Active ingredients: mesalamine
Inactive ingredients: Hard Fat base

For more information, go to or call 1-800- 678-1605.

Source: National Library of Medicine. Last updated October 9, 2020.