A friend of mine started doing Adderall about 7 months ago. It's not his prescription, but he gets it for free from another friend of ours. He snorts it, rather than taking it orally.
I'm really not too worried about it, but his girlfriend is. She really wants him to stop, which makes sense. Not only is it physically bad for him, but if his dad catches him, he'll get shipped off to Reform School.
There are lots of people who argue that, physically, it wont hurt you. Speaking from personal experience, I know thats bullshit. But how do I make him see that? We (me and his girlfriend) want to help him, but we dont know how to make him listen to us.
Any advice?

Seriously, the only way to get some one to stop doing a drug that they are really addicted to is to wait for it to fuck up there life some how. If his girlfriend gets really tired of it she will probably break up with him. Maybe then he will quit. Or maybe if he ODs(can you OD on adderall?), or it fucks up his body somehow.
Or maybe you could try talking to him about how horrible it is, or how you hate the ways he acts when he's on it or something.