An epidural injection delivers steroids into the epidural space around spinal nerve roots to relieve pain – back pain, leg pain, or other pain—caused by irritated spinal nerves. The steroid used in the epidural steroid injection reduces the inflammation of those nerves, which is often the source of the pain. It is important to note that an epidural steroid injection should not be considered a cure for back pain or leg pain: rather, the goal is to
help patients get enough pain relief in order to be able to progress with their rehabilitation program. An epidural steroid injection  significantly reduces pain for approximately 50% of patients. It works by delivering steroids directly to the painful area to help decrease the inflammation that may be causing the pain. It is thought that there is also a flushing effect from the injection that helps remove or “flush out” inflammatory proteins from around the structures that may cause pain. In addition to relieving pain, the process of natural healing can occur more quickly once the inflammation is reduced.
Spinal nerves can become inflamed due to irritation from a damaged disc or from contact with a bone spur.
Depending on which part of the spine the inflamed nerves are located in, pain and/or other symptoms (such as
numbness, tingling) may be experienced in different areas of the body, as shown:

Nerve irritation in the cervical spine

• Neck pain, or tingling, numbness
• Shoulder pain, or tingling, numbness
• Arm pain, or tingling, numbness

Nerve irritation in the thoracic spine

• Upper back pain
• Pain along the ribs to the chest wall
• Pain in the abdomen (rarely)

Nerve irritation in the lumbar spine

• Low back pain
• Hip pain
• Buttock pain
• Leg pain, or numbness, tingling

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