For example, it is ill advised not to take ibuprofen because it would increase the risk of bleeding. I wanted to know if there was more detail to this effect.
The mechanism of action is the inhibition of the cyclo-oxygenase degradation of arachidonic acid which is a precursor of the pro-coagulant thromboxane a2 (see http://www.jbc.org/content/274/41/29108.full.pdf) . Inhibition of a pro-coagulant may lead to increased bleeding, as Dr. Weber noted above.