Azathioprine

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Dec 16, 2022

Warnings

Azathioprine Risks, Warnings, and Complications

Azathioprine can cause serious adverse reactions in certain people. Talk to your doctor about alternative treatments if you are at a high risk of complications from azathioprine use. Some of the potential risks of taking azathioprine include:

HIGHER RISK OF CANCER: Long-term use of azathioprine can increase your risk of developing skin cancer and lymphoma. Limit exposure to ultraviolet light as much as possible. Wear protective clothing and sunblock when outdoors.
HIGHER RISK OF INFECTIONS: Azathioprine can weaken your body’s immune system and increase your risk of getting sick from serious infections. Wash your hands frequently and stay away from people who are sick during azathioprine treatment. You should not get certain live vaccines like varicella (chickenpox), yellow fever, and MMR while you are taking this medicine. Call your doctor right away if you develop fever, sudden muscle weakness, or changes in vision or speech.
EFFECTS ON BONE MARROW: Azathioprine can suppress the bone marrow and lead to a lower red and white blood cell count. The risk of this occurring is greater when you are taking higher doses of the medicine. Your healthcare professional will order blood tests to check the level of azathioprine and the number of red and white blood cells in your blood.
LIVER DAMAGE: Azathioprine can cause liver damage in some people. Your doctor may order a blood test to measure liver enzymes and keep an eye on liver function during treatment with this medicine. The risk of liver damage is highest in the first six months of taking azathioprine. Liver function usually returns to normal after the medicine is stopped.

Precautions Before Starting Azathioprine

Tell your doctor if you have ever had an allergic reaction to azathioprine, any of the active or inactive ingredients in azathioprine tablets, or any other drugs. Your pharmacy can give you a list of ingredients.

Give your doctor a complete medical history. Azathioprine may not be right for people with certain health conditions, such as kidney disease or infections.

Give your doctor or pharmacist a complete list of your other medications, including prescription drugs, over-the-counter medicines, vitamins, supplements, and herbal products. This can help avoid possible interactions between azathioprine and your other medications.

Tell your doctor if you are pregnant, could be pregnant, or are planning a pregnancy. Also tell your doctor if you are breastfeeding.

Precautions During Use of Azathioprine

Keep all your healthcare appointments during treatment with azathioprine. Your doctor may want to perform certain blood tests to keep an eye on your blood cells and liver function.

Use birth control to ensure you or your partner do not become pregnant while you are on this medicine. Tell your doctor if you or your partner become pregnant while taking azathioprine.

Talk to your doctor before getting any vaccinations while on azathioprine.

Tell your doctor you are on azathioprine before any surgery, including dental procedures.

Azathioprine Drug Interactions

Certain other medicines can affect azathioprine if administered concomitantly. Azathioprine and other medicines taken together can also increase the risk of severe adverse reactions. Your doctor may change the doses of your medications and/or monitor you carefully for adverse effects if there are known interactions between azathioprine and your other medicines.

The following medications can have possible interactions with azathioprine:

Alkylating agents for cancer such as chlorambucil (Leukeran), cyclophosphamide (Cytoxan), or melphalan (Alkeran)
Blood pressure medications called angiotensin converting enzyme (ACE) inhibitors such as captopril, benazepril (Lotensin), enalapril (Vasotec), lisinopril (Prinivil, Zestril), fosinopril, moexipril (Univasc), quinapril (Accupril), perindopril (Aceon), trandolapril (Mavik), and ramipril (Altace)
Other drugs that weaken the immune system and increase the risk of infection (such as rituximab, tofacitinib)
Antibiotics like trimethoprim and sulfamethoxazole (Septra, Bactrim)
Antiviral drugs like ribavirin (Rebetol, Copegus, Virazole)
Medications used to treat gout such as allopurinol (Zyloprim) and febuxostat
Anti-inflammatory medications called aminosalicylates such as mesalamine (Asacol, Apriso, Pentasa, others), sulfasalazine (Azulfidine), and olsalazine (Dipentum)
Anticoagulants or blood thinners like warfarin (Coumadin)

The above list may not include all the possible interactions with azathioprine. Give your doctor or pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause a serious reaction when used with prescription and over-the-counter medicines.

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