Vicodin causes MORE pain??

Wondering if any of you have read about this in any healthcare journals or know of any sources because I cannot find it...

Was talking with my PA today, and she said she had read some studies conducted on Vicodin use that suggested the use of Vicodin actually INCREASED one's pain perception and caused them more pain than before using it?? Has anyone heard this?? I know from my own experience that yes it does help with pain, but on days that I take say 1 more vicodin than the day before, i am actually in more pain at the end of the night. and i was talking to a friend about this, and she said that the last few times she took it she felt worse afterwards (after the peak effect, that is).

So I'd just like to know if anyone else has heard this and if so, do you have the reference? I'd love to read the studies done! Oh and has anyone else heard if the FDA is still pushing to get Vicodin and Percocet off the market? Just curious.

Thanks!!