April 15, 2011 -- Drinking alcohol and energy drinks together has become trendy, but it can also be risky, a study suggests.
The combination makes drinkers feel more stimulated than alcohol alone. However, it has no effect on the impulsivity and lack of inhibitions that come with drinking, says study researcher Cecile Marczinski, PhD, an assistant professor of psychology at Northern Kentucky University.
''Even alcohol alone will make you feel stimulated and happy," she says. "Mixing in the energy drink makes that more pronounced. Energy drinks have tons of caffeine in them, more than mixing a soft drink in alcohol.''
As a result, those who drink alcohol and energy drinks in combination can be highly stimulated and highly impulsive, but feel like they are less impaired, Marczinski tells WebMD. So they are likely to have poor judgment of what they are capable of doing.
The study is published online in the journal Alcoholism: Clinical & Experimental Research.
In the past few years, young drinkers in particular have been drawn to mixing alcohol with energy drinks, Marczinski tells WebMD.
Despite the trend, she says, very little laboratory research has examined the effects of the combination.
Research has shown the dangers of adding caffeine to alcoholic drinks and marketing them. In November 2010, the FDA warned companies that the caffeine added to some of their alcoholic beverages makes the products unsafe. As a result, some products were removed from the market. Other companies agreed not to make the beverages in the future. Energy drinks also have caffeine, as well as other ingredients such as plant-based stimulants, sugars, and herbs.
Combining Alcohol With Energy Drinks
In the study, Marczinski and her colleagues assigned 56 college students, average age 24, to one of four groups. One group drank alcohol and an energy drink. Another drank alcohol alone. A third group had the energy drink alone. A fourth group drank a placebo beverage.
The researchers gave all participants a behavioral test. For those in the alcohol groups, the researchers waited until the blood alcohol level reached the legal limit to give the test. "We tested their behavior on a computer task that measured their impulsivity," she says.
"We also gave them a questionnaire and asked them how intoxicated they felt," she says. Those who drank the combination said they felt less intoxicated that those drinking alcohol alone, she found.
"Their behavior, especially for impulsivity, which is what we worry about with drinking, was identical between the alcohol and the alcohol plus energy drink condition," she tells WebMD.
The stimulant effect, however, differed. She used a standard scale to measure stimulation. "The stimulating rating with alcohol and the energy drink was double [that of those who had alcohol alone]," she says.
Blood alcohol levels in the group drinking alcohol alone and alcohol and the energy drink were identical, she says.
The study reflects what doctors in the field have been observing for years, says Steven Lipshultz, MD, executive dean for child health at the University of Miami Miller School of Medicine. He was not involved in the study but reviewed it for WebMD.
Lipshultz has published recent research on the dangers of energy drinks. He began to research it after he cared for patients brought in with adverse effects after using the drinks. He is chief of staff at Holtz Children's Hospital.
"It's been known for some time now that the combination of alcohol and an energy drink is much more concerning in terms of adverse events than in terms of an energy drink alone or alcohol alone," Lipshultz tells WebMD.
The new study, he says, confirms other research showing the adverse effects of the combination.
He worries in particular about high-risk people who do not even know they are at high risk. For example, a teen with an underlying but undiagnosed heart rhythm disorder may be especially susceptible to the effect of the combination.
The reason the energy drink boosts the adverse effects of drinking can be explained simply, Lipshultz says. "Normally, if you drink alcohol over a period of time, your body has a governor. You become sleepy, tired, and ultimately pass out. That's the way the body protects itself. "
However, with the combination of alcohol and energy drink, that ''governor" for sleepiness is inhibited, he says.
"We don't think there is a good reason to use this combination," Lipshultz says.
Perspective of Energy Drink Companies
Asked to comment on the study findings, Elaine Lutz of 5-Hour Energy gave WebMD this statement:
"We do not condone mixing 5-Hour Energy with alcohol. Our call center is specifically instructed to advise consumers that we do not recommend use of our product with alcohol."
"This study has no relevance to 5-Hour Energy. Unlike other products, 5-Hour Energy is a low-volume dietary supplement, making it inherently less compatible with alcohol. Further, our product is not carbonated and contains no sugar."
The product's aim is to help adults manage energy needs and be more productive in their work lives, she says.
A spokesman for Red Bull, another energy drink, says that the study "confirms the beneficial effect of improving cognitive performance when energy drinks are consumed on their own."
It also shows the well-known adverse effects of alcohol drinking on cognitive performance, he says.