Codeine has always had a mild stimulant effect for me. Is why I've always had a soft-spot for the stuff probably. That and being the obvious fallback opi anyway. I find it quite stimulating for the first couple hours followed by a few hours of light monginess and slight noddiness. Dose and tolerance dependent, naturally.
It's defo mentally stimulating for me, I always end up chatting away to my housemates or typing year-long IMs when I'm on codeine. Definitely noddy though. Well it was at the beginning, and I loved it, but now it takes vomit inducing doses.
Well, more so. All codeine doses are vomit inducing unless taken up the back passage I'd imagine. My housemate saw me drinking mine the other day and said 'why the fuck do you not just mix it with juice?'
I have no reasonable answer to that.
edit: this thread is actually giving me that watery mouth and an overactive gag reflex, time to get out ha.