Yes, I have done this before. It was about two years ago. I drank two of the Zicam Cough Mist Max bottles, chased by grapefruit juice or water... Disgusting, but much more tolerable than downing a ton of syrup or pills. That would be something like 1000-1100mg IIRC. Let's say that's something between 15-17mg/kg. I had fasted before this, taken an assortment of vitamins, had a bunch of water on hand, etc. Basically I had taken all the harm reduction steps I could possibly think of.
When it started to come on it immediately hit me, and I stumbled upstairs to my room. I had prepared my room and had it pitch black. I was also using headphones to play Biosphere "Substrata" (Norway ambient) on my CD player. Anyway, to alleviate any tension I completely focused on the music and let it take me away. My whole ceiling lit up with miniature stars, and the music seemed to be pulsating like crazy; my whole physical being seemd to move with it. I soon "lost" my physical self, and began to think in a very calculating, cold manner, looking back on some significant events - both good and bad - in my life. I thought about a relative that had died of a reckless and unfortunate overdose, past girlfriends, experiences, etc. in a very foreign way. It's hard to verbalize, but I saw things from a perspective I would never assume otherwise.
Visually, I was seeing very abstract, almost dreamlike faint pictures that were hard to focus on. I could visualize my thinking, they were vivid but synthetic looking dashes of color appearing in my periphery. It was more like I could DEEPLY and articulately draw from my memory bank and see my thinking in vivid pictures.
Throughout all of this, and as I alluded to before, I lost the feeling of my physical self. Some would call it ego death. When I "searched" for myself, all I could find was my right leg. I had the weirdest sensation of all my thoughts and actions originating from that physical area.
I remember when this track came on vividly:
http://www.youtube.com/watch?v=0-mJPxUt8RE
It samples the old series Twin Peaks, and when Briggs begins talking about his "vision" I remember hearing the voice and kind of clinging to the edge of reality for a moment. It helped me integrate the experience later on.
Eventually, I just went to sleep. I was so tired. I woke up some hours later, and had almost comical vision distortion, with the scale of everything way off. I felt completely distorted and reptilian when walking to get some water. I promptly went back to bed.
So after maybe ten hours of sleep, I woke up. I felt fine except for a slight headache, like an alcohol hangover. I thought about everything and realized how risky what I had done was. I'm not ashamed to say I cried because I realized how great being in this reality was, being with my family, etc. I was so glad that nothing bad had happened. I hoped to use the impressions that I had taken away from my experience to better myself, or see things differently if need be. This was during a difficult period in my life and the experience helped to put things in perspective and be thankful for the great things I had.
I actually went to work later that day. It was alright.
In conclusion, I have had many experiences with traditional psychedelics, but remember this occasion as a changing and illuminating (ultimately for the better) experience. I can't say it was good or bad, but it was definitely intense. I would not repeat it. Before this I had done half the dose (1 bottle) once before. So this was only my second experience, but I knew how to prepare.
DXM is definitely no joke. With proper discretion, it can facilitate some wonderful experiences, but I certainly believe prolonged use could have severe consequences.
Please be careful, and I hope this (very long) report helps you to formulate an educated decision...
