How often cortisone injections are given varies based on the reason for the injection. This is determined on a case-by-case basis by the health care practitioner. If a single cortisone injection is curative, then further injections are unnecessary. Sometimes, a series of injections might be necessary; for example, cortisone injections for a trigger finger may be given every three weeks, to a maximum of three times in one affected finger. In other instances, such as knee osteoarthritis, a second cortisone injection may be given approximately three months after the first injection, but the injections are not generally continued on a regular basis.
Epidural steroid injections are generally very safe, but there are some rare potential complications. One of the most common risks is for the needle to go too deep and cause a hole in the dura, the tissue that surrounds the spinal cord and nerve roots. When this occurs spinal fluid can leak out through the hole and cause a headache . This headache can be treated with bedrest, or with a blood patch. A blood patch involves drawing some blood from the vein and the injecting it over the hole in the dura. The blood forms a seal over the hole and prevents any further fluid from leaking out.