Replying to FIFA: are painkillers "performance enhancers"?

I've been playing my whole life. Maybe I just don't know the regulations surrounding injections of painkillers but it's something I feel is very wrong in such high caliber games as the world cup. One of the reasons I play futbol is because I feel it is a graceful war. Not just between teams but in the individual sense as well. Fighting through the pain of twisted ankles, bruised up shins, battered minds, and pushing your body to the physical limit; to the point of vomiting - sometimes. Good players will recognize weaknesses and act on them. When your opponent is hurt it gives you the upper hand and its what makes the game so enticing in some matches. Now when that player gets an injection - how is that not performance enhancing? Depending on the "injury" sure there's circumstances but it is still in fact a drug being used in competition. Do other sports do this as well?