Patently disagree with this advice. Addiction is a response to some stress in someone's life. We don't know what this kid has going on outside of his friendship with whoever. If anything, the best thing to do is to BUFF UP that friendship: offer an alternative. You can shoot dope, or you can come hang out with me. In fact, you can shoot dope AND THEN come hang out with me. The 'hanging out with me' is the most important part: someone starts using drugs because they don't have enough of that to begin with; even if they're ALWAYS hanging out with people, maybe they're not being themselves. They're being a different person. Inside, they're isolated and alone. The addiction increases that, as the person comes to rely on the drug to feel better, instead of the time-honored method of commiserating with another person. Maybe continuing to hang out with that friend will save his life. Maybe he'll eventually come to realize....hey, it's more fun to hang out with my bro than to shoot dope, and my bro doesn't like it when I shoot dope, and he's stuck with me through all of this, I value his friendship more than I value dope' whereas if his friend stops hanging out with him, he'll just be one more example to the addict of someone he/she cares about abandoning him/her.

The idea of OP is rooted in a puritanical, moralistic thinking about addiction, which has been the basis for our treatment of addicts for over 50 years and which we now know to be ineffective. Addicts need MORE love, MORE compassion....we need to do everything we can to offer them a robust life that's an alternative to drugs, and friends are absolutely a part of that.

Don't ditch your junkie friends: recognize they're in a super bad place and stick with them. The more you let them know it's going to be okay, the better chances of it actually being okay in the future.