An epidural steroid injection is a commonly used, minimally invasive procedure used in the treatment of leg, arm, back and neck pain caused by irritated spinal nerves. Epidural steroid injections, or ESI, can relieve pain that is caused by disc herniation, spondylolysis, or spinal stenosis. Epidural steroid injections cover the nerve root with potent anti-inflammation medicine (steroids) to stop the pain from causing nerve root irritation. Patients who undergo an epidural steroid injection can expect pain relief to last anywhere from several days to several years, depending on their condition. The goal of ESI is to lessen or remove pain so patients can resume their normal activities and work on a physical therapy program.