Steroid injections have been used for many years in spinal disorders. Scientists think they have an anti-inflammatory action. The steroid isn't always injected into the disc. It can be used around the nerve root where the inflammation occurs.
Steroid injection directly into the disc causes the disc to dissolve. Researchers suggest the polymerizing effect of the steroid helps the disc heal itself. Polymerization is a chemical reaction that occurs causing molecules to link together. The result is decreased back pain and sciatica.
The long-term effect of concern is the ability of the steroid to dissolve healthy tissues around the damaged disc. The short-term benefit is avoiding major back surgery.