used it once in my life and think it was two pills, it kept me awake for just under 3 days no bullshit, I was beginning to get paranoid and remember thinking it was about 10x stronger than ephedirne even the first few times ya take it. certainly will make you concentrate better, but I can see how that could very easily be used too often and for the wrong reasons. I can imagine someone using it for finals or a tough mental project, but for pre gym use or for a football game or something very athletic, wow think I would have had a heart attack lol.