it depends on what type of pain killer it is. first, i'll give you a little background on pain killers.
pain killers are also called opiates or opiods. they come from poppy. that's enough background.
snorting ___:
tylenol: don't do it. the active "pain killing" ingredient in tylenol is ace, which will burn your nose, and will give you a burning drip in the back of your throat. it will do absolutely nothing, tylenol isn't even an opiate.
vicodin/percocet: there really isn't any point in snorting vicodin, you might as well just pop it instead, because snorting it doesn't give you any extra effects. the active ingredient in vicodin is hydrocodone, often called "hydros" for short. the active ingredient in percocet, or "percs" is oxycodone. oxycodone IS different from oxycontin.
oxycontin: also called OC, or oxy. if you get oxy, the second most popular way of taking it is by snorting (also called "railing") it. be very careful with oxycontin, as it is much, much stronger than hydros and percs. if you do a full 80mg OC with no tolerence, you will OD, but you won't necessarily die.
you could also plug your opiates, instead of taking them or snorting them.
these are the most popular opiates that are on the street, or that you could get in high school. i'm just assuming you are in high school, if i'm wrong don't be offended.
obviously there are many more opiates that are much stronger, but i'm going under the assumption that if you have access to those, then you probably know whether or not you should snort them.