^ I'd say different, they're both H1 blockers - but diphenhydramine also inhibits 5-HT reuptake, and is anticholinergic as well!
I'd say the biggest differences would come from acrivastine's lack of anticholinergic activity.
I really wouldn't make it a habit.. I had bad trips when I took Opiods with DXM... Stick with DXM and only that and no combos and you will feel pretty good.
^+1
I've never done this combo but I've done both on their own a bunch of times. I don't see any reason to combine them, I take pretty high doses of dxm(850+mg) and it's probably not safe to throw in another 600mg diphenhydramine
lets just sum it up like this:
weak, annoying hallucinations
unbearable body load
distracting fractals
and to top it off
massive hangover.
File under D for "dont bother"