If you look at what a can of redbull contains, it's not unhealthy if you buy the 10 cal/sugar free version. It contains B vitamins, taurine (an amino acid) and about 70mg of caffeine for the under 10oz can. They also use citric acid instead of the cost cutting phosphoric acid which causes calcium leeching.

The aspartame and sucralose may or may not be a problem for you.