Only in very rare circumstances, the effect it has on me is it makes my hyper, everyone here drinks it last nite was studet nite and vodka and redbull is only £1 a glass. I had 5 lol. Combined with about 5 or 6 smirnoff ices bottles, and a long island iced tea. so i was quite drunk come 2am. Vodka and Redbull can make u feel like complete shit though the next day, cus sometimes if i have say 6+ i will stay up the whole nite. You right its not good for your system and some places have banned redbull. Its like having lots of strong coffee i guess but with a shit load of energy in it. I dont recommend a long island ice tea if you wanna stay sober though lol. Hits u like a ton of bricks it had 4 spirits in it. Vodka Bacardi Cointrau Gin. Bleuh i felt that one lol.