What Really Happens To Your Body When You Mix Alcohol And Caffeine

You've probably heard of an Irish coffee, which is a cup of coffee mixed with whiskey and cream. Mixologists may be able to tell you that a combination of energy drinks, Schnapps, and Crown Royal is known as a "Vegas Bomb" shot (via Chef Iso). But at the other end of the spectrum, pick up a bottle of an energy booster and you may find a warning advising you against combining it with alcohol. You have to wonder: Just what exactly happens when you combine alcohol and caffeine? If it's so dangerous, the idea of combining whiskey into coffee and Red Bull with vodka would be far too risky to even consider, right? 

Before we understand the combined effects of alcohol and caffeine in one's system, it's important to know just what happens when you ingest both substances separately. While alcohol can slow down one's reflexes by affecting brain chemistry (via American Addiction Centers), caffeine increases one's energy by numbing the effects of certain chemicals that induce sleep (via EatingWell). If one substance makes you more alert while the other makes you slower to react, is it possible these substances simply cancel each other out, or are there far more serious reactions one could have when consuming both at once?

Real Simple reached out to Dr. Seema Bonney, MD of the Anti-Aging and Longevity Center of Philadelphia in order to better understand the combined effects of liquor and caffeine on the human body. According to Dr. Bonney, drinking both substances at once can have three distinct effects on a person, with the first being a sort of "placebo effect" on your intoxication level.

When consuming alcohol and caffeine together, the caffeine in your body somewhat numbs the calming, drowsy effects alcohol has on the body. While you may be a couple of shots into a Vegas Bomb or espresso martini, you'll feel fine and assume you've just gotten better at handling your alcohol, unaware that the alcohol's effects are being "masked" by the caffeination. The second noticeable effect is that you will begin to feel increasingly dehydrated, as both substances are diuretics — substances that increase the production of urine (via National Collaborating Centre for Environmental Health). 

It's best, Dr. Bonney recommends, to consume water throughout the day and between each cocktail to keep your hydration up. The third effect may not be noticeable at first, but it is no less a cause for concern. Consuming large amounts of alcohol and caffeine together can have potentially dangerous repercussions on one's heart, as well as one's regular sleeping patterns. While Dr. Bonney doesn't say to stop consuming Vegas Bombs or Irish coffee, it is suggested to do so with moderation and awareness.