It can rid itself of some particulates, and small oral, daily doses of graphite are able to achieve this long term. But if your talking about a butyl or teflon particle that is loose in your vial from the septum, it's basically there to stay. It is chemically inert and may expell very slowly. A short term corticoid is good (like Prednisolone @ 5-10mg/d) untill the swelling dies, but if infection has compounded it, corticoids are to be avoided and a NSAI/AB stack is best. Once your immune system calms down, it just forms a small cystic scar over the particle and it probably won't bother you again. I am sure we all have these. That's why I never use lower than a 22g point to brew or extract with because it destroys the septa so quickly. All of us that inject probably remember a time when a shot hurt for no good reason. It may have gotten hot at the site but not raised, and then been gone in a week or so. That's probably all it was. Persistant pain or large particles that can not be broken down may need surgical help, but it can work itself out with time in many cases right through the very spot that it entered with shallow injections.