Understanding ulcerative colitis (UC)

Ulcerative colitis (UC) is an autoimmune disease. It causes your immune system to attack parts of your body. If you have UC, your immune system causes inflammation and ulcers in the lining of your colon.

UC can be more active at times and less active at others. When it’s more active, you have more symptoms. These times are known as flare-ups.

To help prevent flare-ups, you can try to decrease the amount of fiber in your diet or avoid certain foods that are too spicy. However, most people with UC also need the help of medications.

Imuran is an oral medication that can help you manage symptoms of moderate to severe UC, including stomach cramps and pain, diarrhea, and bloody stool.

According to recent clinical guidelines, the preferred treatments for inducing remission in people with moderate to severe UC include:

Doctors usually prescribe Imuran for people who’ve tried other drugs, such as corticosteroids and aminosalicylates, that didn’t help relieve their symptoms.

Imuran is a brand-name version of the generic drug azathioprine. It belongs to a class of drugs called immunosuppressants. It works by decreasing your immune system response.

This effect will:

  • reduce inflammation
  • keep your symptoms in check
  • lower your chance of flare-ups

Imuran may be used alongside infliximab (Remicade, Inflectra) to induce remission or on its own to maintain remission. However, these are off-label uses of Imuran.


Off-label drug use means a drug that’s approved by the FDA for one purpose is used for a different purpose that hasn’t yet been approved. However, a doctor can still use the drug for that purpose. This is because the FDA regulates the testing and approval of drugs, but not how doctors use drugs to treat their patients. So, your doctor can prescribe a drug however they think is best for your care.

It may take up to six months for Imuran to begin to relieve your symptoms. Imuran can reduce the damage from inflammation that can lead to hospital visits and the need for surgery.

It’s also been shown to reduce the need for corticosteroids that are often used to treat UC. This can be beneficial, since corticosteroids can cause more side effects when used for long periods of time.

For people with UC, the typical dosage of azathioprine is 1.5–2.5 milligrams per kilograms of body weight (mg/kg). Imuran is only available as a 50-mg tablet.

Imuran can also cause potentially serious side effects. While taking it, it’s a good idea to see your doctor as often as they suggest. That way, they can watch you closely for side effects.

The milder side effects of Imuran can include nausea and vomiting. The more severe side effects of this drug are:

Increased risk of certain types of cancer

Using Imuran for a long time may increase your risk of skin cancer and lymphoma. Lymphoma is a cancer that affects your immune cells.

Increased infections

Imuran lowers the activity of your immune system. This means your immune system may not work as well to fight off infections. As a result, the following types of infections are a fairly common side effect:

Even though they’re common, infections can still be serious.

Allergic reaction

Symptoms of an allergic reaction usually happen within the first few weeks of treatment. They include:

If you have these symptoms, contact your doctor right away.


Pancreatitis, or inflammation of the pancreas, is a rare side effect of Imuran. If you have symptoms such as severe stomach pain, vomiting, or oily stools, call your doctor right away.

Imuran may interact with the following medications:

If you’re currently taking one of these medications, your doctor may have you discontinue its use before you begin Imuran.

They may also recommend an Imuran dosage for you that’s smaller than the typical Imuran dosage. A smaller dosage will help to minimize drug interactions.

Your doctor may suggest Imuran if drugs like aminosalicylates and corticosteroids haven’t worked to control your UC symptoms. It may help reduce flare-ups and help you manage your symptoms.

Imuran comes with the risk of serious side effects, including an increased risk of cancer and infections. However, taking Imuran can also help you avoid the serious side effects that are associated with long-term corticosteroid use.

Talk with your doctor to determine if Imuran is a good choice for you.