Also DXM is heavy on the liver enzymes so make sure that you are not mixing things when taking it. Then there is the whole play on the serotonin receptors so you need to make sure you are not taking SSRI as you can give yourself serotonin syndrome. I use to us DXM pretty regularly when I was 16-17, almost every Saturday night by myself in my room, I use to thoroughly enjoy spending the evening with my head down on my computer desk for hours at a time "watching the movies in my head" as i use to call it. My dose was 718mg, or something, 1 standard 8 oz bottle of maximum strength tussin.
Just be careful and read about it and dont abuse it or assume you can ever pass for sober and youll be fine. Take it during the day and go out in public and you will appear like some crazy bug eyed drunk dude who looks like he is about to kill someone, with this crazed "dxm face" thing going on.