College students that mix alcohol with caffeinated energy drinks are at higher risk for alcohol-related injuries than students who drink regular cocktails, according new research from Wake Forest University School of Medicine.

The researchers found students who drank the energy cocktails were twice as likely to be hurt or injured, twice as likely to require medical attention, and twice as likely to ride with an intoxicated driver. The study also found students who drank alcohol mixed with energy drinks were more than twice as likely to take advantage of someone else sexually, and almost twice as likely to be taken advantage of.

"We knew anecdotally — from speaking with students, and from researching internet blogs and Web sites — that college students mix energy drinks and alcohol in order to drink more, and to drink longer," said Dr. Mary Claire O'Brien, lead researcher and associate professor of emergency medicine and public health sciences at Wake Forest, in a news release. "But we were surprised that the risk of serious and potentially deadly consequences is so much higher for those who mixed energy drinks with alcohol, even when we adjusted for the amount of alcohol."

O'Brien and her colleagues conducted a Web-based survey of more than 4,000 college students from 10 universities. Students were asked approximately 300 questions about alcohol use, its consequences, and other health risk behaviors.

Of the students who reported drinking alcohol in the past 30 days, 24 percent said they consumed alcohol mixed with energy drinks. Students who were male, older, white, intramural athletes, Greek society members or pledges were significantly more likely to consume alcohol mixed with energy drinks.

O'Brien said she was not surprised by the responses since energy drink companies typically flaunt non-essential ingredients like ginseng, which some companies claim enhances libido. The main ingredient in energy drinks is caffeine. O'Brien used the analogy that mixing caffeine (a stimulant) with alcohol (a depressant), is like getting into a car and stepping on the gas pedal and the brake at the same time.

"Students whose motor skills, visual reaction times, and judgment are impaired by alcohol may not perceive that they are intoxicated as readily when they're also ingesting a stimulant," said O'Brien. "Only the symptoms of drunkenness are reduced — but not the drunkenness. They can't tell if they're drunk; they can't tell if someone else is drunk. So they get hurt, or they hurt someone else."

The Food and Drug Administration (FDA) limits caffeine to 65 milligrams per serving of a food or beverage. Since energy drinks are currently not regulated by the FDA, they can contain as much as 300 milligrams of caffeine in a single serving, the researchers said.

The findings were reported at the annual meeting of the American Public Health Association in Washington, D.C., which concludes Wednesday.