I never really got into supplements much, back in the day I used to take creative but never really got into the pre workouts. My girlfriend recently bought one from Costco, the other day I took it before I went to the gym, it was insane I did get some energy but the most noticable thing was as I was running on the treadmill my arms and legs were tingling and kinda burning, I was like WTF I didn't know if I was about to pass out or what. When I mentioned it to my gf she said whatever pre workout it was had a lot of niacin. I remember back in the day in like high school people used to say NIacin helped you pass drug test, I dont think it actually did anything but I remember once or twice taking heavy doses and feeling that same feeling.