The steroid medication is used to decrease the inflammation and or swelling of the piriformis muscle. The local anesthetic, numbing medication can temporarily stop the spasms.
After the Injection
The local anesthetic will wear off approximately six hours after the injection. Your pain may briefly return before the steroid medication takes effect. The return of pain does not mean the block did not work. The steroid or anti-inflammatory medication may not start working for 24 to 72 hours. Sometimes it can take up to one week for the steroid to work or take effect.
You may experience soreness over the injection site for a day or two after the procedure. This soreness may be the direct result of the needle being inserted into the piriformis muscle and from the medication injected. The piriformis injection can last anywhere from days to months. If you achieve partial sustained relief following the first piriformis injection, then additional injections may be repeated to give you a greater degree of sustained pain relief.