Seizure/Pass Out While on Psilocybin Mushrooms

Recently my brother (20M), some friends, and I (20M) decided to take psilocybin mushrooms together just for fun and to bond some more. The trip was going perfect. We were all having fun and laughing and it was just an all around great experience. We then decided to smoke weed about two hours into the trip. Smoking weed is nothing new for any of us as we do it pretty regularly. 30 minutes or so after we all smoke, my brother was sitting in a chair and out of nowhere his whole body completely locks up. Stiff as a board and gripping the arm rests it looked like he was being possessed. Eyes completely open as well. After about 6-8 seconds he snaps out of it and starts looking around the room extremely confused. He’s sweating profusely and extremely thirsty. We were all panicked trying to make sure he was ok. Me and another friend tried helping him up to his bedroom where he could step away and we could make sure he was ok and that it wasn’t going to happen again. He could barely walk and was still extremely sweaty. He stopped sweating but he was shaking very hard and we didn’t know if he was scared or had some form of chills. We stayed up with him for hours afterwards to make sure that nothing else would happen. He was slightly incoherent but we’re sure he was just still being influenced by the mushrooms. He eventually started to feel better and he explained to me that a few years ago he was with a different group of friends and he had taken psilocybin mushrooms and smoked weed at the same time and had passed out for a few seconds.

My brother is an extremely healthy individual. He goes to the gym every day, eats very healthy, and gets plenty of sleep. He has cardiomyopathy but I’m not sure if it’s related to the situation. He has never had a seizure or passed out outside of those two instances. He has obviously not touched any type of substance since that incident.

I couldn’t find any answers online but being able to understand what happened would bring my brother and I more peace of mind. I don’t think I’ve ever been more scared in my life and I thought I was going to lose my brother that night.