There are some great replies as to the dangers of IV 2C-E, so much so that it makes me wish I never did it. I actually had a great experience; no pain, no physical discomfort, and even a slight rush. Since my experiences were so different, I've decided to post them just as a counterpoint.
However, I was deep into the thick of a DOB trip when I decided I needed a little something extra. The previous day's DMT trips left me with a thirst for fast acting hallucinogens, so I decided to inject 2C-E. Had I been sober, I probably wouldn't have done this.
But I did, and I liked it. It certainly kicked up the visuals of DOB a notch at 2-4 mg, and was euphoric enough for me to continually readminister every half hour to hour or so, doubling the dose each time until my hands were too trembly to continue. The largest dose was 14-16 mg. Again, none of these doses seemed to have any negative impact physically, and were pretty damn fun.
In the name of science I tried this route again, only this time sober. I took about 4-6 mg this time, and noticed a slight rush and a short trip followed. It felt quite different this time, because of course I was on just one drug, and I didn't think it was anything special. The trip seemed to lag the shot by about five to fifteen minutes, which directly contradicts the instant increase in intensity while on DOB. Despite a lack of physical discomfort, I probably wouldn't do this again.
It's interesting that my experiences were so different than everyone elses in this thread. It makes you wonder what you actually are getting when you buy RC's. Illusion25 compared it to alcohol IV; that's like a bee sting to the arm with no benefit whatsoever, unless something fun has been dissolved in the alcohol first. That comment surprised me, since the 2C-E injections were pain free. Again, how can we be sure we all injected the same drug?