Prednisone is very similar to the hormone cortisone, which the body manufactures.
Prednisone is used to treat many illnesses.
In part, prednisone acts as an immunosuppressant. The immune system protects against foreign bacteria and viruses. In some illnesses, the immune system produces antibodies, which become overactive and cause undesirable effects. Prednisone suppresses the production of antibodies. This suppression can make it slightly harder for you to fight off infection but also stabilizes the immune system if it is overactive.