AZATHIOPRINE (Imuran®) INFORMATION SHEET

Developed by Andy Thompson MD FRCPC

What is Azathioprine?

Azathioprine is an immunosuppressive medication (suppresses the immune system). Azathioprine is used to treat Systemic Lupus Erythematosus and many other types of arthritis and rheumatic disease. Occasionally doctors use Azathioprine for diseases other than arthritis.

How does Azathioprine work?

Azathioprine works by suppressing the body’s immune system. Although this suppression can make it slightly harder for you to fight off infections, it also stabilizes the immune system if it is overactive.

What is the usual dose of Azathioprine?

• Azathioprine is available in 50 mg tablets.
• The usual starting dose is 50 to 100 mg per day (1 to 2 tablets)
• The maintenance dose is based on your body weight with the standard dose ranging from two tablets (100 mg) to four tablets (200 mg) per day.

How often do I take Azathioprine?

Azathioprine is only taken ONCE OR TWICE A DAY as prescribed by your doctor.

Who should NOT take Azathioprine?

• Patients who have had a previous reaction to Azathioprine.
• Women who are pregnant, planning on becoming pregnant, or are breast feeding.
• Men who are planning pregnancy with their partner.
• Some patients with diseases of the liver, kidney, or blood disorders.
• Patients with active infections (talk with your doctor first).

When will I start to feel the effects of Azathioprine?

Azathioprine does not work right away. It could take about 8 to 12 weeks before you start feeling better. The maximum effect can take up to 6 months. If your doctor changes the dose it can take another 8 to 12 weeks before you feel the effects.

What should I AVOID while taking Azathioprine?

• Do not get pregnant

Which Medications are safe to take with Azathioprine?

Most medications can be used safely with Azathioprine. As an example, some of the medications your doctor may use safely with Azathioprine include: Acetaminophen (Tylenol), Prednisone, Other DMARDs (i.e. Hydroxychloroquine), and Biologics (i.e. Etanercept, Infliximab, Anakinra).

• ALLOPURINOL, a medication used for gout, can interact with Azathioprine. Please tell your doctor if you are taking Allopurinol.

What are the side-effects of Azathioprine?

MORE COMMON side-effects include:

• Nausea, vomiting, and diarrhea
• Aching in the joints
• Skin rash - May be itchy

RARE side-effects include:

• Fevers and generally feeling unwell
• Liver - Azathioprine may irritate the liver. This does not usually cause symptoms but may be found on blood tests. It is uncommon and usually reversible when regularly monitored with your monthly blood tests.
• Blood Counts - Azathioprine can cause a drop in the numbers of red blood cells (which carry oxygen), white blood cells (which are needed to fight infection) and platelets (which help to stop bleeding). Because we monitor the blood count very closely, it is unusual for this to be a serious problem.
• Infection - Any infections or fevers should be taken seriously and reviewed by your doctor.
• Malignancy - When used for long periods of time, Azathioprine may be associated with a small increased risk of skin or blood cancers.

How can I help to minimize the side-effects of Azathioprine?

• Take your Azathioprine as prescribed by your doctor.
• Take your Azathioprine with food to help reduce stomach upset.

Do I need to have regular blood tests while taking Azathioprine?

YES, you will need BLOOD TESTS EVERY 1 - 3 MONTHS. This is important to make sure the Azathioprine is having no harmful effects on your liver or bone marrow.

How do I stop the Azathioprine?

You do not need to wean yourself off the Azathioprine. It can simply be stopped. However, your condition may “flare” after you stop the medicine.

What should I do if I miss a dose of Azathioprine?

• If you forget to take your Azathioprine at the usual time but remember later on the same day, take the missed dose immediately.
• If you forgot to take yesterday’s dose, skip yesterdays dose and take your usual dose for today.

Is Azathioprine safe in pregnancy?

• You should avoid pregnancy while taking Azathioprine.
• If you are planning a family or become pregnant while taking Azathioprine NOTIFY YOUR DOCTOR IMMEDIATELY.
• You should not breast feed while taking Azathioprine.