PEOPLE who mix highly caffeinated energy drinks with their alcoholic beverages may be at increased risk for injury—both intentional (fights, violence and attempted suicide) and unintentional (falling, tripping and motor vehicle accidents)—according to a new study by the University of Victoria’s Centre for Addictions Research of BC (CARBC) published in the March issue of Journal of Studies on Alcohol and Drugs.

In the first systematic review of published research on the subject, Audra Roemer, University of Victoria doctoral student in clinical psychology and the study’s lead researcher, found that of the 13 studies that fit their research criteria, 10 showed evidence of a link between the use of alcohol mixed with energy drinks and an increased risk of injury compared to drinking alcohol only.

“The stimulant effects of caffeine mask the sedative effects of alcohol,” says Roemer. “Usually when you’re drinking alcohol, you eventually get tired and you go home. Energy drinks mask that, so people may underestimate how intoxicated they are, end up staying out later, consume more alcohol, and engage in risky behavior and more hazardous drinking practices.”

However, given the variability in the relatively few studies on the topic thus far, they were not able to statistically determine the exact extent of the increased risk associated with mixing alcohol and energy drinks.

To get a closer look at the relationship between alcohol, energy drinks and injury, and in response to calls from Health Canada and others for more research in this area, Roemer is currently running a controlled emergency room study in Vancouver and Victoria.

“When we look at alcohol alone, there’s a clear dose-response relationship: when you drink more, the risk goes up,” she explains. With one or two drinks, the risk of injury is twice as likely as when completely sober. With six drinks, there’s a six-fold increase in risk. But when alcohol is mixed with energy drinks, Roemer has observed what she calls a surge in response: according to preliminary analysis based on a relatively small sample size, the risk of injury is somewhere in the order of 20 times greater.

Alcohol mixed with energy drinks and risk of injury: A systematic review was co-authored by CARBC Director Tim Stockwell and funded by the Canadian Institute of Health Research.