I've done 2c-I quite a few times, and these are my experiences with it. Sadly I had to witness my girlfriend have a seziure, and I've read a little bit about 2C-I causing them. I think it was more cuz of her current state of health combined with a drug like 2C-I, but for the weeks leading up to the event she had been drinking heavily every day. She was getting headrushes a lot more often, either from smoking weed and then a cig, or sometimes just a cig alone.
This would happen from time to time, but then it seemed to be happening a lot more frequently then normal. I attribute this to her lack of self care with constant drinking and bad nutrition. After we went to vegas she went back to drinking all day every day. She has never had a seizure. This wasn't her first time taking 2C-I, but it was her second. Her first time dose was what I had left over in the bag, and I let her snort it all. This was a pretty decent dose nasally, and she tripped balls. Overall she enjoyed it, and wanted to try it again.
So it was a beautiful Saturday and I decided I wanted to trip at the beach. She only wanted a little bit, and her dose was around what she took before, maybe even less. This time she took it orally though, and had already been drinking since we got up. This dose was 10 MG or less, but unfortunately my MG scale had been stolen out of someones car that I lent it to. I erred on the side of caution, but I've taken at least 4 times as much. So I dropped a combo of something and off we went. Well on the way I wanted to smoke a bunch of bowls before we got there, so then we would be high for the come up. I made the mistake of not recalling her previous blackouts, and really didn't think anything of it.
So we are chilling at the beach, and I decide to have a cig and watch the ocean. Well she wanted one too, so I gave it to her. After I was done she had a decent amount left, but I started to notice that she was trembling. At first it reminded me of alcohol W/D, so I ran over to her and told her to stop smoking the cig. She then mutters something about rainbows over her vision, and now I see the trembling is all over her body and is turning into full tremors. I grab her, and then she goes into convulsions. It was one of the scariest moments of my life. I had gone to school to become an EMT, so luckily I was able to recall what to do and I tried not to panic.
She convulsed for a full on minute or so (hard to say, but I was ready to call 911 if it went too much longer) and quickly started snoring as soon as it ended. It was a Grand Mal Seizure, and it was scary as fuck. I carried her to the car so no one would be alerted, and she slowly came back to consciousness. She really had no recollection of the event until I told her she had a seizure. All she remembers was her vision turning into a gigantic rainbow and thinking she was gonna die.
So I think the 2C-i enabled it to happen, but it was her poor health that actually caused it. I've read that people have had gnarly headrushes off of 2C-I, even when coming down and laying in bed. Luckily mentally after a week or so she said she felt pretty normal, but her body was pretty beat up. It was around 4 bowls of medical pot, but the dose was so small I really cant see how that would be the sole factor.
Weeks later and the image is still burned in my head. That was my worst nightmare to have someone have an adverse reaction to chemicals I gave them, let alone my girlfriend. Needless to say no more 2c-i for her!
I really liked this chemical prior to this, but now I am afraid to give it to anyone else. Also I've noticed as the dose is increased, the crappy body stimulation grows. I took around 30ish MG, and while yes I was having a good time trippin balls, the tension flowing through my body was almost to much to bear, I remember at different parts of the trip how bad I felt for putting my body through this shit. I was drinking beer and I kept on squeezing the bottle with all my might, but good to know it didn't break

. I love the visuals and mental aspects at high dose, but the body is too much. I doubt Ill ever do that again.
Also for those who haven't tried a combo of acid and 2c-i, its awesome! I took 1 hit of alright acid, but one normally isn't enough for me. I snorted around 5-10 mg, just two little lines. It upped the visuals immensely (There were pretty much none) and sent me into a completely positive exploratory mode of thought. I just sat in my backyard thinking about the universe and all this crazy shit. I would most likely do this again, just not with snorting. Not sure how the best timing, 2C-I first of course but not sure how long after to drop the acid.