http://orthoinfo.aaos.org/topic.cfm?topic=A00560

Facet injections and epidural steroid injections are a key component to nonsurgical pain management for chronic neck and back pain. The results may last anywhere from a week to more than a year. The
injections are often used in conjunction with other nonsurgical treatments such as therapy and medication. The injections are performed with fluoroscopic guidance to localize accurately the placement of the
needle. Local anesthesia is used prior to the injection. The injected material is a mixture of cortisone and anesthetic. Some side affects include increased pain, headaches, rash, short term increase in blood sugar.