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Rectal mesalamine is used to treat certain inflammatory bowel conditions, such as ulcerative colitis. Common side effects include gas, rectal pain, or hemorrhoids. Rarely, rectal mesalamine can cause kidney stones. It is important to drink plenty of liquids while using rectal mesalamine to reduce this risk.

Uses

What is rectal mesalamine used for?

Rectal mesalamine is commonly used for the following conditions.

  • Ulcerative colitis, which is an inflammatory bowel condition that affects your large intestines
  • Proctosigmoiditis, which affects the lower end of your colon
  • Proctitis, which is inflammation of the anus and lining of the rectum

Rectal mesalamine may also be used for other conditions as determined by your health care provider.

How does rectal mesalamine work (mechanism of action)?

Rectal mesalamine may work by blocking certain natural substances in your large intestine, which reduces inflammation.

How is rectal mesalamine supplied (dosage forms)?

Brands and other names

  • Canasa
  • Rowasa
  • Sfrowasa

Dosage forms and strengths

  • 4 g/60 mL enema
  • 1 g rectal suppository

See also: Mesalamine

How should I store rectal mesalamine?

Rectal mesalamine should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of rectal mesalamine?

The most common side effects of rectal mesalamine are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Gas
  • Flu
  • Fever
  • Leg or joint pain
  • Hemorrhoids or rectal pain
  • Hair loss

There may be other side effects of rectal mesalamine that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of rectal mesalamine?

While less common, the most serious side effects of rectal mesalamine are described below, along with what to do if they happen.

Severe Allergic Reactions. Rectal mesalamine may cause allergic reactions, including a specific type of allergic reaction called DRESS. DRESS stands for drug reaction with eosinophilia and systemic symptoms. It is also sometimes called multi-organ hypersensitivity. This is a reaction that can affect multiple parts of the body including your liver, kidneys, and heart. Stop using the medicine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Shortness of breath, trouble swallowing, or throat tightness
  • Swelling in your feet, ankles, or legs
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain
  • Dark-colored pee
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Severe Skin Reactions. Rectal mesalamine can cause severe skin reactions, called Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP), that can lead to death if not treated. If you develop a rash, stop mesalamine and call your health care provider right away. Get emergency help if you have any of the following symptoms of SJS.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes

Inflammation of the Heart Muscle. Myocarditis is when your heart muscle becomes inflamed or irritated. This can affect how well your heart pumps blood. Rectal mesalamine can cause the immune system to cause more inflammation around the heart muscle. Contact your health care provider right away if you have chest pain, shortness of breath, or trouble breathing.

Kidney Problems. Rectal mesalamine can cause swelling of a small part of your kidneys’ filters called the tubules. This condition, known as tubulointerstitial nephritis (TIN), can cause your kidneys to not work as well as they should. Stop using rectal mesalamine and call your health care provider right away if you have any of the following symptoms of TIN. 

  • Increased or decreased amount of urine (pee)
  • Nausea or vomiting
  • Fever
  • Rash
  • High blood pressure
  • Irregular mood swings
  • Confusion or drowsiness
  • Swelling throughout your body or weight gain

Kidney Stones. Rectal mesalamine may cause kidney stones. Drinking plenty of water can help prevent kidney stones. Tell your health care provider right away if you develop severe pain in your side or back or have blood in your urine (pee). Your pee may look pink, red, or brown.

Worsening of Ulcerative Colitis Symptoms. Rectal mesalamine can cause worsening of ulcerative colitis symptoms. This happens when you develop a reaction to mesalamine. It may be difficult to tell if your symptoms are caused by ulcerative colitis or using mesalamine. Tell your health care provider right away if you have any of the following symptoms or if they get worse while you are using mesalamine.

  • Stomach cramps or pain
  • Bloody diarrhea
  • Fever
  • Headache
  • General feeling of being unwell, tired, or not having your usual energy
  • Skin itching or rash
  • Pink eye (conjunctivitis)

Warnings & Precautions

Who should not use rectal mesalamine?

Allergies to Ingredients. People who are allergic to any of the following should not use rectal mesalamine.

  • Canasa
  • Mesalamine
  • Rowasa
  • Sfrowasa
  • Any other medicine known as a salicylate or an aminosalicylate
  • Sulfites (some rectal mesalamine products contain sulfites)
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific rectal mesalamine products they stock.

What should I know about rectal mesalamine before using it?

Do not use rectal mesalamine unless it has been prescribed to you by a health care provider. Use it as prescribed. Read and follow the “Instructions for Use” when using mesalamine. Ask your health care provider if you have any questions about how to use it. 

Do not share rectal mesalamine with other people, even if they have the same condition as you. It may harm them.

Keep rectal mesalamine out of the reach of children.

Make sure to drink enough liquids while using rectal mesalamine. This can help prevent kidney stones. See the Side Effects section for more details. 

Rectal mesalamine may cause your urine (pee) to turn reddish-brown if it comes into contact with bleach, such as in some toilet water. Tell your health care provider if your urine is reddish-brown when it leaves your body (before it touches the toilet water).

Rectal mesalamine can make your skin more sensitive to light from the sun, sunlamps, and tanning beds. This is called photosensitivity. Exposure to this light can cause severe sunburns, blisters, and swelling. If you need to be in sunlight, wear sunscreen, a hat, and clothing that covers your skin.

People who are 65 and older can be at greater risk for some side effects from rectal mesalamine. Talk to your health care provider about your risks if you are in this age group. Keep all of your appointments for follow up with your health care provider, labs, or other testing.

What should I tell my health care provider before using rectal mesalamine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if rectal mesalamine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Other Medicines and Supplements. Rectal mesalamine may interact with other medicines and supplements. Before using rectal mesalamine, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how rectal mesalamine could affect pregnancy or harm an unborn baby. Tell your health care provider if you are or plan to become pregnant.

Breastfeeding. Rectal mesalamine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will advise you if you should use rectal mesalamine while breastfeeding. If you breastfeed while using mesalamine, watch for diarrhea in your infant.

Interactions

Does rectal mesalamine interact with foods or drinks?

There are no known interactions between rectal mesalamine and foods or drinks.

It is unknown if drinking alcohol will affect rectal mesalamine.

Does rectal mesalamine interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using rectal mesalamine.

  • A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which is in many prescription and OTC products for pain, swelling, and fever
  • Azathioprine (Azasan), which is a medicine that suppresses your immune system
  • 6-mercaptopurine, which is a medicine to treat certain cancers

This may not be a complete list of medicines that can interact with rectal mesalamine. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much rectal mesalamine?

If you or someone else has used too much rectal mesalamine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of rectal mesalamine?

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only use the next dose. Do not use double or extra doses.