Mixing energy drinks with alcohol could be a risky combination, leading to a greater risk of accidents and injuries, research from Canada suggests.
The caffeine contained in energy drinks can make people feel wide awake and encourage them to drink more than normal.
Medics say this could also cause problems sleeping and a raised heart rate, although more research is needed.
Charity Drinkaware does not recommend mixing alcohol and energy drinks.
Mixing spirits and liqueurs with energy drinks, such as Red Bull and Monster, has become increasingly popular - in pubs and clubs, and at home.
But recent research suggests that drinking alcohol mixed with high-caffeine energy drinks could be more risky than drinking alcohol on its own, or with a more traditional mixer.
This is because it can make people "wide awake drunk" - a result of the stimulating effects of caffeine and the brain-slowing effects of alcohol.
What are the risks?
In a review of 13 studies published between 1981 and 2016, researchers at the University of Victoria, Canada, found a link in 10 studies between intake of alcohol mixed with energy drinks and an increased risk of falls, fight and accidents.
But they said they were unable to pin down the size of the injury risk because of the varied nature of the studies and the difficulty of comparing results.
When it comes to the question of whether mixing alcohol and energy drinks is harmful to health, larger studies are still needed to work this out.
At present, the Food Standards Agency and the Committee of Toxicity says the evidence is not clear.
What is in energy drinks?
Energy drinks contain high levels of caffeine, usually about 80mg in a 250ml can - equivalent to a mug of instant coffee.
In comparison, a 330ml can of classic Coca-Cola contains 32mg and a can of Diet Coke 42mg.
Energy drinks also contain lots of sugar as well as other ingredients, such as glucuronolactone and taurine, and sometimes vitamins and minerals or herbal substances.
Some smaller "energy shot" products can contain as much as 160mg of caffeine in a 60ml bottle.
Photo: Getty Images vodka with energy drink Red Bull is a popular option in bars and clubs