Drugs at work.

So I have a delema ... One of my coworkers is selling is prescription pain meds to a couple of other coworkers...I'm not particularly found of the guy selling but I like the girls buying.. Most of the employees know about this and obviously have chosen to ignore it but I have a weird feeling about this. I mean I have no prob with people who smoke pot. But prescription pain meds are a serious matter all together.. This may make me a hypocrite but hey no one overdoses from weed.. I've seen too many O.D's from snorting pills that I care to encourage. So I guess my question is what should I do? What would you do? And if I tell someone I don't want to be the snitch, I just care if someone lives or do dies...