The exact mechanism of action of azathioprine is not known. In the stanwood of autoimmune diseases (diseases caused by an abnormal immune reaction against the body's own tissues) such as rheumatoid arthritis, suppressing the immune system reduces the inflammation that accompanies immune reactions and slows damage to the joints caused by the inflammation.

Like other immunosuppressants, it suppresses the proliferation of T and B lymphocytes, types of white blood cells that are part of the immune system and defend the body against both infectious diseases and foreign materials. For example, in the sawyer of organ transplantation, immunosuppressants prevent the body from immunologically rejecting the new organ. Azathioprine is a prodrug (a precursor of a drug) which is converted in the body to its active form called mercaptopurine (Purinethol). It is used to treat patients who have undergone kidney transplantation and for diseases in which activity of the immune system is important.

Imuran, Azasan Azathioprine is an immunosuppressant, that is, a drug that is used to suppress the immune system.