Standard drinks on a night out could be a lot more harmful for you than you realise, according to new research.
Experts claim that mixing energy drinks with alcohol can be as bad for teenagers as taking cocaine, with the effects lasting well into adulthood.
Researchers from Purdue University in Indiana found adolescent mice given an energy drink were not more likely than a control group to drink more alcohol as adults.
However, when those high levels of caffeine were mixed with alcohol, they showed physical and neurochemical signs similar to mice given cocaine.
Professor Van Rijn said, "It seems the two substances together push them over a limit that causes changes in their behaviour and changes the neurochemistry in their brains. We are clearly seeing effects of the combined drinks that we would not see if drinking one or the other."
They concluded that teenagers drinking the mix of drinks would be affected in how they deal with substances like alcohol and drugs when they are adults - suggesting that those who use cocaine in later life would need to take more to get high.
Professor Van Rijn added, "Mice that had been exposed to alcohol and caffeine were somewhat numb to the rewarding effects of cocaine as adults. Mice that were exposed to highly caffeinated alcoholic drinks later found cocaine was not as pleasurable. They may then use more cocaine to get the same effect."
A spokesman for Red Bull, which is often mixed with vodka, declined to comment, directing questions to the British Soft Drinks Association.
BSDA director deneral Gavin Partington said, "There is no indication that energy drinks have any specific effect (negative or positive) on adults or teenagers related to alcohol consumption. Last year the European Food Safety Authority (EFSA) concluded that it is unlikely that caffeine interacts adversely with energy drinks or with alcohol.
"However, anybody drinking alcohol should do so in moderation, whether or not it`s mixed with an energy drink."
The findings have been published in the journals Alcohol and PLOS ONE.