Recently I was legitimately prescribed DXM, and I must say, I am disappointed. At the proper therapeutic dose, I am glad that it suppresses my chronic drowsiness, but everything else about it is pretty awful.
@theacidtest has got it spot on: "I found it to be a gross and somewhat sickly high." Yesterday I used it recreationally for the first time (40mg sublingually) but it only brought about everything that's undesirable in the way of amphetamine side effects: feeling weirdly hot though without normal sweating, desert-dry eyes which are now red and sore, my penis and scrotum have gotten all tight and withdrawn (way more so than when having a cold shower/swimming in cold water!), dry mouth with occasional pasties, and really high blood pressure which hasn't gone down yet. Oh, and the gut-rot began straight away and has rendered me sick and weakened for the past 12 hours=( Also, I occasionally hallucinate something tiny and quick zooming past my peripheral vision field - which, interestingly, has always been a symptom I experience when pulling allnighters to study. It's only annoying if I keep bothering to turn my head when I see it in the corner of my eye (looks like a super-fast fly or mozzie). And as for DXM's intended effect of promoting wakefulness: despite my moderately large recreational dose, I have actually dozed off a few times already!