Canasa (Mesalamine)

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Mesalamine (Canasa) reduces bleeding, mucus and bloody diarrhea caused by inflammation of the rectal area. It is used to treat active ulcerative proctitis (ulcerative colitis confined to the rectum).

How should it be used?

Follow the doctor’s instructions about how often and how long to use Canasa.

This medicine is used in the rectum – not by mouth!

Try to go to the bathroom before using the medicine (suppository).

Use the suppository when you can lie down on your side and hold the medicine in.

  • Wash your hands before using the suppository.
  • Remove the wrapper. Moisten the suppository with cool water.
  • Do not hold too long because it will get soft and begin to melt.
  • Lie on your side and insert into the rectum. Use your finger to push it in all the way.

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, don’t use the missed dose.Do not use 2 doses at one time.

Special Precautions/Instructions

Before you starting taking this medicine tell the doctor about any of the following:

  • Medications (including over the counter), vitamins, herbal products.
  • Allergic to sulfazalazine, mesalamine, or anything in this medicine.
  • Allergic to aspirin, non-steroidal anti-inflammatory drugs (NSAIDS), foods, preservatives, or dyes.
  • Have kidney problems.
  • Have had inflamed pancreas (pancreatitis).
  • Are pregnant, plan to become pregnant, or breastfeeding.
  • Have a condition where you could develop myocarditis or pericarditis.

Side Effects

Common side effects include: diarrhea, headache, gas or flatulence.

Possible serious side effects include a reaction to the medicine that includes cramps, sharp abdominal pain, bloody diarrhea, and sometimes fever, headache and rash. Stop using and tell your doctor right away if you get any of these symptoms.

In rare cases, the sac around the heart may become inflamed (pericarditis). Tell your doctor right away if you develop chest pain or shortness of breath, which are signs of this problem.

In rare cases, patient using Canasa develop worsening colitis (pancolitis).

Very few patients using Canasa may have mild hair loss.

Other side effects not listed above may also occur in some patients.

Contact your doctor immediately if you experience signs of an allergic reaction including:

  • Diarrhea
  • Feeling sick
  • Fever, shivering/chills, rash
  • Muscle and bone pain
  • Kidney problems (changes in the amount of urine or color of urine)
  • Tiredness, dizziness
  • Itching
  • Swelling
  • Trouble breathing

Storage Conditions

This medication should be stored away from direct light, heat, and humidity. It should be stored at 77 degrees F and should NOT be frozen. Keep out of reach of children.


Call the national poison control center 1-800-222-1222 or 911 in the event of overdose. Symptoms of an overdose include vomiting, diarrhea, sore throat, fever, chills, and other signs of infection.

Pediatric Use

The safety and efficacy of this drug in pediatric patients have not yet been established.