Mesalamine for Ulcerative Colitis

Medically Reviewed by Sabrina Felson, MD on June 09, 2024
5 min read

Mesalamine is a medicine for ulcerative colitis and other types of inflammatory bowel disease (IBD). It's part of a group of anti-inflammatory medicines called aminosalicylates (5-ASA). These medicines bring down swelling in the intestine lining and help it heal.

Sulfasalazine (Azulfidine) was the first 5-ASA drug used to treat IBD, but it can cause a lot of side effects. Most people who can't take sulfasalazine can safely take mesalamine.

Mesalamine is often the first drug prescribed for mild-to-moderate ulcerative colitis.

It's not clear how mesalamine brings down inflammation. It may lower your immune system response or block chemicals in your body that cause inflammation.

Mesalamine is used to treat mild-to-moderate ulcerative colitis. It may be the first medicine your doctor prescribes to prevent and treat symptom flare-ups.

This medicine could also be an option if you have a milder form of ulcerative colitis called ulcerative proctosigmoiditis. And it's a treatment for ulcerative colitis in the sigmoid colon, the bottom part of your colon that attaches to your rectum.

This medicine also treats Crohn's disease, although it doesn't help as much as it does for ulcerative colitis.

You take mesalamine by mouth or rectum. The medicine in each brand of mesalamine is the same, but the delivery method is different.

Delayed-release tablets and capsules don't release the medicine until it reaches the intestine, so they're more targeted to certain parts of the intestine. Extended-release capsules let out the medicine slowly so the effects last longer. Mesalamine tablets and capsules have a special coating on the outside to help the medicine reach your intestine.

You take each type and brand of mesalamine in a different way.

Delayed-release tablets

  • Asacol HD. Take it with or without food once a day in the morning.
  • Lialda. Take it with food once a day.

Extended-release tablets

  • Apriso. Take it with or without food once a day in the morning.
  • Delzicol. Adults take it two to four times a day with or without food. Children take it twice a day.
  • Pentasa. Take it with or without food four times a day.


  • Canasa. Place this medicine directly into your rectum once or twice a day. Taking both a suppository and a pill may relieve your symptoms better than pills alone.


  • Rowasa. This medicine comes as a fluid that you put into your rectum and colon. You take Rowasa once a day and leave it in for 20 to 40 minutes. An enema may help with inflammation in the left side of your colon.

Read the medicine label for more complete directions on how to take your type of mesalamine. Follow the instructions and take only the amount your doctor prescribed.

Try to drink extra fluids while you take mesalamine. Staying hydrated will protect your kidneys.

Don't stop taking the medicine, even if you feel better, without checking with your doctor. If you have any questions about how to use mesalamine, ask your doctor or pharmacist.

If you have mild-to-moderate ulcerative colitis, mesalamine could help put you into remission and keep you there. Remission means you have few or no symptoms. Between 40% and 70% of people who take mesalamine see an improvement in their symptoms, and up to 20% go into remission.

Most people start to improve within 1 to 3 weeks after they start taking mesalamine. If you don't get relief from symptoms that quickly, be patient. It can take up to 6 weeks for the medicine to put you into full remission.

If your symptoms don't improve after a month on mesalamine, your doctor might add a steroid, TNF inhibitor, or other medicine to help it work better.

Mesalamine may not be safe if you have certain medical conditions, including:

  • An allergy to aspirin or sulfasalazine
  • Heart, liver, or kidney disease
  • A blockage in your stomach or intestines
  • Swelling of the heart muscle, called myocarditis
  • Swelling of the sac around the heart, called pericarditis
  • Skin problems like eczema or atopic dermatitis

Mesalamine may cause more liver, kidney, and heart risks in older adults. Your doctor might need to adjust the dose to prevent these problems.

You'll need to avoid Apriso if you have the inherited condition phenylketonuria (PKU). This medicine contains the artificial sweetener aspartame, which people with PKU must avoid.

Let your doctor know if you're pregnant, you could become pregnant, or you're breastfeeding. There haven't been enough studies to show that mesalamine is safe to take during pregnancy. You can safely use this medicine while you breastfeed, but let your doctor know if your baby has diarrhea or other side effects.

Mesalamine is considered safe overall. Serious side effects are rare, but some people do have mild side effects when they take this medicine. The most common ones are:

  • Muscle or joint aches or pains
  • Nausea and vomiting
  • Belly pain
  • Headache
  • Rash

Tell your doctor about any side effects that bother you or that don't improve. You may need to change the dose or take a different medicine.

Don't be surprised if you see an empty shell from the capsule in your stool. This is normal and it's usually not a problem. But if you see the whole capsule, it means the medicine isn't getting into your intestine. You may need to switch to another brand.

Mesalamine can make your skin more sensitive to the sun. Try to avoid sun exposure while you're taking this drug. If you do have to be outdoors during the day, wear UV-protective clothes, sunscreen, and sunglasses to shield your skin.

Rarely, this medicine can cause a serious reaction called mesalamine-induced acute intolerance syndrome. The symptoms can be confusing because they look like ulcerative colitis. Tell your doctor if you're taking mesalamine and you have:

  • Stomach pain or cramps
  • Bloody diarrhea
  • Fever
  • Headache
  • Weakness
  • Rash

Pancreatitis is another rare side effect of mesalamine. It's swelling of the pancreas that causes symptoms like severe belly pain, nausea, vomiting, and a fast heartbeat.

Get medical help right away if you have symptoms of a severe allergic reaction, like:

  • Rash, hives, or skin blisters
  • Swelling of your face, eyes, lips, tongue, or throat
  • Sores or blisters in your mouth
  • Trouble breathing or swallowing
  • Wheezing

Because mesalamine sometimes harms the liver or kidneys, your doctor might test your liver and kidneys to make sure they're healthy before prescribing this medicine. Once you start taking mesalamine, your doctor should schedule regular visits to check that the medicine is helping you and it isn't causing side effects.

Mesalamine can interact with other medicines. Some interactions increase side effects. Others make one or both of the drugs stronger or less effective.

These are some of the medicines that interact with mesalamine:

  • Anti-inflammatory drugs such as aspirin, ibuprofen, and naproxen
  • Antacids
  • Bismuth subsalicylate
  • Digoxin, a blood pressure medicine
  • Azathioprine, an immune-suppressing drug that prevents rejection after an organ transplant
  • Mercaptopurine (Purixan), a chemo drug
  • Blood thinners like warfarin (Coumadin) and heparin

Tell your doctor and pharmacist about any other medicines you take with mesalamine, including any supplements and medicines you buy over the counter.