Cortisone is a synthetic version of cortisol. There are many different compounds in this steroid injection group, as well as in tablet forms. The main purpose is to help decrease your body’s defensive response and help treat conditions such as inflammation, arthritis, allergic reactions, some eye & skin conditions, hormone and immune system disorders. It can greatly reduce pain and even help with conditions like trigger finger, when it is injected locally. It is not thought to repair joint surfaces.