I've had what I believe to be a seizure twice on two seperate mushroom trips based on what those around me told me. I just woke up feeling like every muscle hurt.
The first time was many hours into a mushroom tea trip and all of a sudden if thought I was just peaking. Everything became a flow of extreme colour in my field of vision, reality totally disappeared and when the colours faded away I saw 4 terrified friends standing over me and they reported that my eyes rolled into the back of my head and I started shaking like crazy. It happened again years later on a solo mushie trip as I was walking up the stairs from my basement. I did not drop mushrooms for almost 10 years after the 2nd time. I always suspected its related to some other alkoloid in the zoomers as it's NEVER happened on anything but mushies to me not even 4-aco-dmt at "heroic dosages".