I'll second that about morphine, which really messed up my head when I had it. And coming off it, yes, can be very bad with some people - someone I know suffered a couple of weeks of paranoid delusions after morphine.Have rested my arm more this week and do my physio religiously, so hopefully next few weeks it will start to show. When do you have your OP? My shoulder kept dislocating when I did mine, and they couldn't fit me in to operate for 2 weeks. Be very careful if you're on morphine for the pain, trust me you are better off without it, it's another battle to come off that crap!! Took me a month to get over the side effects of that. Barely take any tablets, rather have the pain.
For me it was before and after some surgery a while back, and they were almost obsessive about eliminating pain to the point of insisting on pumping the stuff into me until I could feel none. I'm really not that bothered about mild pain, and I ended up lying and saying I had none just to get them to stop the morphine.