For many years I have been performing Prolotherapy on patients who come to see me already taking blood thinners, including Coumadin and aspirin. Let me first say that in all my years of doing Prolotherapy on patients on Coumadin, I have never had a problem. I do let them know that there is an increased chance of bleeding and/or bruising of course, and on very very rare occasions someone on Coumadin may develop a hematoma (where blood accumulates in the muscle), but I have never actually had a patient develop a hematoma.
Even if it did happen, the normal treatment is to apply heat to it and wait until it resolves.
In regard to aspirin, most folks who take this for blood thinning are taking a baby aspirin or 81mg per day. This amount of aspirin can thin the blood and I have not found it strong enough to inhibit the prolotherapy treatments. So if you are on aspirin for heart disease prevention, then by all means continue taking it and don’t worry about it inhibiting the Prolotherapy injections.