I don't think you that likely to be sick, if that is what is worrying you. It really depends on how you are generally; do you easily feel ill in a car, coach or train?
Most of the rides are really fast, that is short time, and so even if you start to feel a bit off colour, you usually don't get time to be sick. If it makes you feel that way, you probably won’t ride it again, but it's got to be worth trying it once. Go an hour or two after eating.
As for more serious reactions, there would have to be something already wrong with someone to be harmed by a ride at Disney, they are really very safety conscious! After all, their reputation is vital and they want people to have a good time, not be hurt or feel ill.
The CM’s have to clean up if someone is sick, so not doubt they carefully work out how much the average person can take when designing these rides!