He's prescribed a specific dose of a medication by a licensed medical practitioner. True, some of them are fucking morons just like any other profession. But generally speaking, they rarely do things that fuck their patients up (even if only to avoid law suits).120mg per day is a very high dose. The PDR (physician's desk reference) recommends 40mg/day as the max. That's pretty conservative these days though. Don't worry, it's not going to kill him. He should be fine long-term so long as he doesn't deviate from the doctor's prescription regimen. He will definitely have withdrawal if he stops abruptly though. Same symptoms as meth withdrawal. Exhaustion (possibly severe), lack of motivation, and extreme hunger are pretty common. Some people also experience anxiety and extreme restlessness. Basically it's unpleasant and can easily keep you from being anything resembling a functioning person for a couple of days or up to a week if he's unlucky.Amphetamines are the one drug I have interest in. The rest don't tempt me in the least. Don't even care for the way they feel. Well... okay, PCP was kind of fun, lol. But my point is that I've done quite a bit of reading up on amphetamines, and he'll be fine. Biggest risk at 120mg/day long term is eventual dependence (addiction), IMHO.