I have heard that taking Niacin, vitamin supplement, will bring you out of a trip. Just be careful not to overdo the Niacin or you'll get what they call a "Niacin Flush". Won't hurt you, just make you feel hot and all flush. One last, and most important point about shrooms or acid. If you are already bugging out about eating them, chances are you're gonna BUG THE FUCK OUT when you do eat them. You should be in a really good mental state when you do them or you stand a good chance of fuckin' yourself up.