The uses of Imuran include: Azathioprine is used with other medications to prevent rejection of a kidney transplant. It works by weakening your body's defense system (immune system) to help your body accept the new kidney as if it were your own. This medication belongs to a class of drugs known as immunosuppressants.
Azathioprine is also used to treat patients with severe rheumatoid arthritis who have not responded to other medications (e.g., nonsteroidal anti-inflammatory drugs/NSAIDs such as ibuprofen). Rheumatoid arthritis is thought to be caused by the immune system attacking the joints. Early treatment of rheumatoid arthritis with more aggressive therapy such as azathioprine helps to reduce further joint damage and to preserve joint function.