What is a cortisone/corticosteroid injection?

Cortisone is a steroid that is produced naturally in the body. Synthetically-produced cortisone can also be injected into soft tissues and joints to help decrease inflammation. While cortisone is not a pain reliever, pain may diminish as a result of reduced inflammation. In orthopaedics, cortisone injections are commonly used as a treatment for chronic conditions such as bursitis, tendinitis, and arthritis.