First, platelets go to the area, and release several substances including one particular substance called thromboxane, and other clotting factors are recruited to
the area, a clot then a scab eventually forms. This process
occurs everywhere
in the body to stop a bleed.
NSAIDs like ibuprofen and vioxx inhibit the formation of some of the molecules involved in the clotting cascade, so that when bleeding occurs, the body's normal response to the bleeding is impaired.