What is Azathioprine?

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 other purposes not listed in this medication guide.

What is the most important information I should know about Azathioprine?

Do not use this medication without telling your doctor if you are pregnant. It could cause harm to the unborn baby. Use an effective form of birth control, and tell your doctor if you become pregnant during treatment.

Taking azathioprine may increase your risk of developing cancer. Talk with your doctor about your specific risk.

Azathioprine can lower the blood cells that help your body fight infections. This can make it easier for you to bleed from an injury or get sick from being around others who are ill. To be sure your blood cells do not get too low, your blood will need to be tested on a regular basis. Your kidney function may also to need to be tested. Do not miss any scheduled visits to your doctor.

Call your doctor at once if you have a fever, chills, sore throat, body aches, weakness, muscle pain, easy bruising or bleeding, mouth sores, pale stools, darkened urine, or severe nausea, vomiting, and diarrhea.

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

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.

Do not receive a “live” vaccine while you are being treated with azathioprine and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you.

What should I discuss with my healthcare provider before taking Azathioprine?

Do not take this medication if you are allergic to azathioprine.

Taking azathioprine may increase your risk of developing cancer. Talk with your doctor about your specific risk.

Before taking azathioprine, tell your doctor if you are allergic to any drugs, or if you have:

• liver disease
• any type of viral, bacterial, or fungal infection; or
• if you have recently received chemotherapy treatments with medications such as cyclophosphamide (Cytoxan), chlorambucil (Leukeran), melphalan (Alkeran)

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication.

FDA pregnancy category D. This medication can cause harm to an unborn baby. Do not use azathioprine without telling your doctor if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.

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.

Azathioprine can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Azathioprine Side Effects

What are the possible side effects of Azathioprine?

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

Call your doctor at once if you have a serious side effect such as:

• pale skin, easy bruising or bleeding, unusual weakness
• fever, chills, sore throat, body aches, weakness, muscle pain, flu symptoms
• severe nausea, vomiting, or diarrhea
• severe pain in your upper stomach spreading to your back, fast heart rate
• pain or burning with urination
• stomach pain, loss of appetite, dark urine, clay-colored stools, and jaundice (yellowing of the skin or eyes); or
• white patches or sores inside your mouth or on your lips

Less serious side effects may include:

• mild upset stomach, nausea, diarrhea, loss of appetite
• hair loss; or
• skin rash

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

Azathioprine Interactions

What other drugs affect Azathioprine?

Before taking azathioprine, tell your doctor if you are taking, have taken, or need to take any of the following medicines:

• allopurinol (Zyloprim)
• mercaptopurine (Purinethol)
• methotrexate (Rheumatrex, Immunex)
• a blood thinner such as warfarin (Coumadin)
• cyclosporine (Neoral, Sandimmune)
• olsalazine (Dipentum), or sulfasalazine (Azulfidine)
• sulfamethoxasole and trimethoprim (Trimpex, Proloprim, Bactrim, Septra, others); or
• an ACE inhibitor such as benazepril (Lotensin), captopril (Capoten), fosinopril (Monopril), enalapril (Vasotec), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), or trandolapril (Mavik)

This list is not complete and there may be other drugs that can interact with azathioprine. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

What should I avoid while taking Azathioprine?

Avoid being near people who have colds, the flu, or other contagious illnesses. Contact your doctor at once if you develop signs of infection.

Do not receive a “live” vaccine while you are being treated with azathioprine and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you.