First of all, it is full of stims, so you might have reacted badly to so much stim. Secondly, what they have is a propiertary blend, so there is no real way of knowing what is actually in there, and what could be causing the nausea. My personall recommendation would be to switch for some non-stim based preworkout supplement, such as DSpark. It has no stims in it, so these will not cause you problems, and it is not a propiertary blend, so you will be at least aware of the complete list of ingredients in it. I use it, and I love it - it is so good to have this much energy and such strong pumps during a workout wihtout having to use stims.