From HSS.edu:
Platelet-rich plasma (PRP) is produced from a person's own blood. It is a concentration of one type of blood cell (platelets), which is critical for blood clotting. This concentration is injected to an injured or diseased part of a person’s body to accelerate the healing of damaged tendons, ligaments, muscles, bones and joints. A key advantage of PRP injections is that they can reduce the need for opioids, or even over-the-counter anti-inflammatory medications. In fact, use of anti-inflammatories should usually be ceased at the time of PRP treatment, because the platelet-rich plasma optimizes the initial inflammatory response involved with healing.