okay, this is really quite simple. BEFORE you buy or lift a bottle of tussin, check to see what the ACTIVE INGREDIENTS are. it's that simple. if it says guafinesin(sp?), don't get it. unless you relish the thought of puking your guts up. i wouldn't exactly consider that a trip, but, hey, different strokes for different folks, right?
if it says Dextromethorphan Hydrobromide/HBr, then get it. there's another type of DXM, Dextromethorphan Polistyrex(sp?), which is the extended release form of DXM. meaning, it takes longer to hit (if it ever does), and it tends to last a bit longer. also, going from simple reasoning, i think it would be safe to say that higher doses are needed to have a higher plateau trip. but, i've never had experience with polistyrex before, so i have no real info on it.
and, to help you out, here are a couple brands that *do* contain DXM:
CVS Tussin Max Strength Cough (Blue Box) 15mg/5ml
Vicks Cough (Green Line, i believe) 30mg/5ml
the vicks comes in 4oz bottles and contains as much dxm as an 8 oz bottle of the cvs tussin, so you go do the math. i think i'd rather drink 4 than 8...