Why don't most narcotics have any effect on me?

I've been prescribed vicodin, darvocet, percocet, and morphine after several surgeries I've had, and the only one that did anything was morphine (it was in a pca pump after major stomach surgery). I was either hyperventilating or hallucinating, so I asked them to take me off of it. Most recently, I was prescriped vicoprofen (vicodin and ibuprofen) for having a molar extracted, and it did nothing for me, so I threw it away. The only other one that worked was stadol (used as a test medicine in my epidural during the birth of my first son) and it was great. However, most don't work. Is there a reason for this?

not everyone can convert drugs like codeine into morphine, actually most people can't. that is why the morphine worked, but the other derivatives didn't. i don't know what the drugs you tried were, we call them all different names, but if they were derivatives of morphine then that could make the difference. there are allot of other medications that can be used to treat pain, particularly post surgery, anti-inflammatory's are particularly useful, narcotic analgesics have a place, but are not suitable for everyone. considering how you felt on morphine i think you could safely give that one a miss next time.

here's my bad answer: you're not taking enough. chewing 'em up also helps.