Trigger point injection (TPI) may be an option for treating pain in some patients. TPI is a procedure used to treat painful areas of muscle that contain trigger points, or knots of muscle that form when muscles do not relax. Many times, such knots can be felt under the skin. Trigger points may irritate the nerves around them and cause referred pain, or pain that is felt in another part of the body.

In the TPI procedure, a health care professional inserts a small needle into the patient’s trigger point. The injection contains a local anesthetic or saline, and may include a corticosteroid. With the injection, the trigger point is made inactive and the pain is alleviated. Often, a brief course of treatment will result in sustained relief. Injections are given in a doctor’s office and usually take just a few minutes. Several sites may be injected in one visit.