diphendramine will fuck you up. You won't be happy, and you will have a hard time acting straight. Its not a recreational drug, and using it as one isn't good.

My experiences with it started out as feeling sort of drunk, (placebo), then feeling really really tweaked, like i couldn't sit still, and i felt like i would die if i did. I felt like ever seccond if was about to fall asleap and then jerked awake. This continued until it became unbearable. i then start to see stuff, like people who aren't there, and really really random crap, and then i become a zombie. bad shit.

don't fuck with it.
also, if you ever need bennadryl, taking it recreationally will increase your bodies tolerance to it, and require you to take more than the standard dose