Skip the espresso martini: The dangers of mixing caffeine and alcohol

By Samar Mahmoud, PhD | Fact-checked by Anastasia Climan, RDN, CD-N
Published May 2, 2023

Key Takeaways

  • Beverages that combine caffeine and alcohol are particularly popular among underage drinkers and young adults. 

  • Combining caffeine and alcohol is a dangerous practice which puts consumers at increased risk of alcohol-related harms, such as alcohol poisoning and risky behavior.

  • HCPs should advise patients to avoid caffeinated alcoholic drinks, or discuss the dangers with those who choose to partake.

Whether it's an Irish coffee, an espresso martini, or a mixed drink made with liquor and a can of Red Bull, the combination of alcohol and caffeine is a popular one, particularly among young people. However, consuming caffeine and alcohol at the same time can be more dangerous than you think. 

What happens when caffeine and alcohol are mixed?

When these two substances are combined, the caffeine, acting as a stimulant, masks the depressant effects of alcohol, according to a report by the CDC.[] This makes drinkers feel more alert than they would if they were drinking alcohol alone. 

In other words, the combination of caffeine and alcohol makes drinkers underestimate their intoxication, which may lead to more alcohol consumption, increasing the risk of alcohol-related harm.

These potential harms may include alcohol poisoning, driving under the influence, and risky sexual activity, according to the CDC report. 

There is a common misconception that drinking caffeine with alcohol functions to “sober up” the drinker. However, this is not true, as caffeine does not affect how the liver metabolizes alcohol and therefore does not lead to lower blood alcohol concentrations. 

Mixing caffeine and alcohol can also elevate a drinker’s blood pressure, increasing the risk for stroke and heart attack, according to the authors of an article in Nutrition Reviews.[] 

Prevalence among young people

Most energy drinks are sweetened carbonated beverages that have high levels of caffeine and may include ingredients such as taurine, guarana, and ginseng. 

According to the CDC, the practice of mixing alcohol with energy drinks is prevalent among young people in the United States. In 2017, 10.6% of students in grades 8, 10, and 12, as well as 31.8% of young adults between the ages of 19 and 28, reported consuming alcohol mixed with energy drinks at least once in the past year. 

Those who mixed alcohol with energy drinks were more likely to report instances of unprotected or unwanted sex, drunk driving or getting in a car with a driver who was drunk, or instances of alcohol-related injuries.

 The article in Nutrition Reviews recounts the dangers that arose after premixed caffeinated alcoholic drinks, including Four Loko and Moonshot, became available for sale. Their safety was called into question when highly intoxicated underage drinkers and young adults began showing up in emergency rooms after having consumed these alcoholic energy drinks. 

This led the US Federal Trade Commission to send a warning letter to manufacturers of these beverages in November 2010, stating that alcoholic caffeinated drinks present “unusual risks to health and safety.”[] The manufacturers voluntarily removed the stimulants from their alcoholic beverages.[]

“Consumers might mistakenly assume that these beverages are safe because they are widely sold,” said David Vladeck, Director of the Federal Trade Commission’s Bureau of Consumer Protection, in the warning letter sent to manufacturers. 

"In fact, there is good reason to believe that these caffeinated alcohol drinks pose significant risks to consumer health and safety. Consumers – particularly young, inexperienced drinkers – may not realize how much alcohol they have consumed because caffeine can mask the sense of intoxication."

David Vladeck, Director of the Federal Trade Commission’s Bureau of Consumer Protection

Potential symptoms of mixing caffeine and alcohol

Because both caffeine and alcohol are diuretics, dehydration is a primary concern when caffeine and alcohol are mixed. Symptoms of dehydration include thirst, dry mouth, passing dark urine, and feeling lightheaded. Dehydration upsets the balance of minerals (salts and sugar) in the body, which affects functioning related to joints, eyes, digestion, the skin, and more.[] 

What this means for you

Healthcare providers have a critical role to play in decreasing the prevalence of this dangerous practice of mixing alcohol and caffeine. HCPs should have open conversations with their patients about their drinking habits and address misconceptions about the effects of combining alcohol and caffeine. For patients who choose to mix alcohol and caffeine, HCPs should discuss the warning signs and symptoms of adverse health effects, including dehydration and elevated blood pressure. 

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