anything in excess is bad for you.
i don't typically drink energy drinks (or much soda for that matter)
but they don't seem to have much of an affect on me unless i have more than 2
and if you drink too many, there's records of people having mild heart attacks.
some of them, like Rockstar, i believe, have warnings on the side.
eh, 1 or 2 aren't gonna hurt ya
but too many can have serious affects