Need a Suggestion on a Movie About Drug Abusers?

Well, I’m a writer (that kind of explains my non-sense questions), and I need suggestions for a movie which retracts the reality of a drug addict. I need it to be REALLY explicit, since I don’t know any addicted, because I’m gonna have to base my descriptions of drug abuse and the addicts life on scenes I catch from movies and books I read. Of Course I’m trying to visit some rehab center to gain information and stuff, but I find it hard to believe they’re gonna let me see what I want. Thanks already! hmm, I will choose a best answer!
– I mean HARD DRUGS, not alcohol