I can understand where you coming from there, I start gagging whenever something is anywhere near the back of my month (i was actually gagging on my toast this morning) try brushing your teeth when your in the shower (don't ask me why) but this actually seemed to help or you could just try doing sometime else while brushing them. Good luck

Try using a toothbrush w/ a smaller head. I actually purchased a child's toothbrush and it's definitely helped with the gagging/throwing up response I get when brushing my teeth.

Yeah, I also have the same thing with me which happens every morning. I know our breath is not fresh every morning so I toothbrush before I eat and when I do that, I feel like throwing up. I noticed it only happens when I haven't eaten anything. Sometimes you only feel like vomiting when you have pushed your toothbrush too deep in your mouth that you almost swallow it. So, what I did was, I just brush my tongue not too deep.