Welcome to SR, Joy
I had some periods in my life (long time ago) when I was using different kinds of legal stimulants - Red Bull was one, for a while. Others were diet pills, not with the intention of losing weight but I liked the effect - nothing like a stronger psychostimulant (I tend to react badly to those) but still uppers. I found myself starting to abuse each of these after a few weeks and then they gave me weird scary symptoms (mostly anxiety, I think) so stopped each time and never even thought about using any other stimulant than coffee for a long time, which I never had problems with.
I think it's like everything: if you find yourself drinking Red Bull to excess and experience negative effects, I would stop. If not, maybe not a problem for you. I do agree with Croissant though about these substances putting us in a limbo between stimulation and crashes. Sugar does that, too.