Do regular painkillers not provide the same relief?
Ibuprofen for example is also an anti-inflammatory painkiller. Or Aspirin, which is also an NSAID.
They don't work near as well or near as long. They also made me sick, easily agitated, in a stuffty mood constantly, had a major loss of appetite, so on and so forth.
When I first started marijuana I was also taking half a painkiller with it as a boost. I soon found out that marijuana alone was completely removing the pain. The munchies also allowed me to start eating again. (I had lost 5-6 pounds due to over the counter pain killers, couldn't eat much at all)