I dont know man

At first I had thought it would be funny if he didn't do any except maybe coffee and beer. Like he's so pissed off all the time cuz he doesnt do anything to relax not even drugs BUT now knowing he doesnt like coffee and has the diet and appetite of a child he probably wouldn't like beer either. If he did drink at all it would have to be sweet enought to not taste the alcohol.

At the end of the dance episode he asks Chris if he's "all out of those pain meds" so it seems he's not against taking prescription drugs for fun. And in another episode (can't remember atm i think it was wolfman?) Hes told he's over the legal limit of "pocket lint" on his person which is obvs supposed to be a weed joke so I'll take that as Dan also smokes weed on occasion.