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.
Imuran is an immunosuppressant that is used to prevent rejection after an organ transplant. Imuran can also be used to treat various chronic (long-term) autoimmune and inflammatory conditions such as Crohn's disease, rheumatoid arthritis and systemic lupus erythematosus. As an immunosuppressant, the drug works by suppressing the body's defense or immune system.