When I started tripping, I would get really nauseous/sick on the come-up of most of them (mushrooms only a little though, and LSD not at all). I remember the first times I did 2C-I, and 2C-E, and 2C-T-2, and AMT, I would feel horrible and puke a dozen times and have a period of time where I wished with everything I had that I hadn't taken this poison... then the come-up would end and I'd enjoy the rest of the trip, but sometimes I'd still experience some lingering body malaise for the whole trip.
As I got more trips under my belt and the years went on, I started feeling less and less of that. For years now, I have felt basically no nausea or body malaise whatsoever from psychedelics. I took 2C-I again a couple of years ago after a long time of not taking it, and I never even got slightly uncomfortable or nauseous or shitty-feeling at any point during the come-up or the trip. I can even take AMT now and only get a bit of a sour stomach. I don't know what changed. The only things I can think of are that maybe my gut 5-HT3 receptors have been beaten into senselessness by all the psychedelics I've done (I had a period in 2006-2008 where I took psychedelics probably 3 times a week on average and the lack of side effects started then and has never disappeared), or else the nausea and body malaise were brought on by disorientation from the transition from sober to tripping (nowadays the transition feels very smooth and doesn't take me by surprise).
When I did used to get nauseous, what would help was laying down. Also my ex taught me a trick she uses that surprisingly really helps me to this day if I get nauseous: press your thumb firmly into your wrist, on the underside, just below where the bones and cartilage of your wrist are, in the center. There's a sort of depression there between two tendons that run up your arm. Press and hold it firmly (also lay down). For me, almost immediately I notice a significant lessening of the urge to throw up and if I hold it and lay down for a few minutes, my stomach will settle.
