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Azathioprine

Generic Name: azathioprine (ay za THYE oh preen)
Brand Name: Azasan, Imuran

Medically reviewed on July 2, 2018

What is azathioprine?

See also: Dupixent

Azathioprine lowers your body's immune system. The immune system helps your body fight infections. The immune system can also fight or "reject" a transplanted organ such as a liver or kidney. This is because the immune system treats the new organ as an invader.

Azathioprine is used to prevent your body from rejecting a transplanted kidney. It is also used to treat symptoms of rheumatoid arthritis.

Azathioprine may also be used for purposes not listed in this medication guide.

Important Information

Some people using azathioprine have developed a rare fast-growing type of lymphoma (cancer). This condition affects the liver, spleen, and bone marrow, and it can be fatal. This has occurred mainly in teenagers and young adults using azathioprine or similar medicines to treat Crohn's disease or ulcerative colitis.

Before taking this medicine

You should not take azathioprine if you are allergic to azathioprine, or if you are pregnant (unless the benefits of treating you outweigh any risks posed by taking azathioprine).

Some people using azathioprine have developed a rare fast-growing type of lymphoma (cancer). This condition affects the liver, spleen, and bone marrow, and it can be fatal. This has occurred mainly in teenagers and young adults using azathioprine or similar medicines to treat Crohn's disease or ulcerative colitis.

However, people with autoimmune disorders (including rheumatoid arthritis, Crohn's disease, ankylosing spondylitis, and psoriasis) may have a higher risk of lymphoma. Talk to your doctor about your individual risk.

While taking azathioprine, you may have a higher risk of developing skin cancer. Talk to your doctor about this risk and what skin symptoms to watch for.

To make sure azathioprine is safe for you, tell your doctor if you have:

FDA pregnancy category D. Do not use azathioprine if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.

Azathioprine can pass into breast milk and may harm a nursing baby. You should not breast-feed while you are using azathioprine.

This medication can affect fertility (your ability to have children), whether you are a man or a woman. Talk with your doctor if you have concerns about this.

How should I take azathioprine?

Your doctor may perform blood tests to make sure you do not have conditions that would prevent you from safely using azathioprine.

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take azathioprine with food to lessen stomach upset.

You may not be able to continue taking other arthritis medications together with azathioprine. Follow your doctor's dosing instructions very carefully.

Azathioprine can lower blood cells that help your body fight infections and help your blood to clot. This can make it easier for you to bleed from an injury or get sick from being around others who are ill. Your blood will need to be tested often.

It may take up to 8 weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.

If you need surgery, tell the surgeon ahead of time that you are using azathioprine. You may need to stop using the medicine for a short time.

Store at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking azathioprine?

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Avoid exposure to sunlight or tanning beds. Azathioprine can increase your risk of developing skin cancer. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

Do not receive a "live" vaccine while using azathioprine. The vaccine may not work as well during this time, and may not fully protect you from disease. Live vaccines include measles, mumps, rubella (MMR), rotavirus, typhoid, yellow fever, varicella (chickenpox), zoster (shingles), and nasal flu (influenza) vaccine.

Azathioprine side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using azathioprine and call your doctor right away if you have any of these symptoms of lymphoma:

  • fever, night sweats, weight loss, tiredness;

  • feeling full after eating only a small amount;

  • pain in your upper stomach that may spread to your shoulder; or

  • easy bruising or bleeding, pale skin, feeling light-headed or short of breath, rapid heart rate.

Azathioprine may cause a serious viral infection of the brain that can lead to disability or death. Call your doctor right away if you have any change in your mental state, decreased vision, or problems with speech or walking. These symptoms may start gradually and get worse quickly.

Also call your doctor at once if you have:

  • signs of infection (fever, chills, sore throat, body aches, weakness, muscle pain, flu symptoms);

  • severe nausea, vomiting, or diarrhea;

  • pain or burning with urination;

  • white patches or sores inside your mouth or on your lips; or

  • liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect azathioprine?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with azathioprine, especially:

This list is not complete. Other drugs may interact with azathioprine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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