What Happens When You Mix Caffeine and Alcohol

Find out if combining caffeine and alcohol into one beverage could put your health at risk — and what the answer means for your espresso martini habit.

espresso martini in a cocktail glass
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Just like biscuits and gravy or peanut butter and jelly, coffee and alcohol can make for a delicious pair. Pouring Bailey's into an iced coffee creates a drink that cools you down while warming you up to your Bumble date. Mixing espresso into a martini makes for a classy-looking beverage that also serves as a pick-me-up. And adding Irish whiskey, sugar, and whipped cream to a hot cup of Joe gives you a grown-up, energizing milkshake.

While these cocktails are surely delicious, is it actually safe to drink a combo of caffeine and alcohol? Here, Jamile Wakim-Fleming, M.D., a gastroenterologist specializing in liver disorders at the Cleveland Clinic, breaks it down.

Is It Safe to Mix Caffeine and Alcohol?

No, sipping on caffeinated cocktails generally isn't a good idea.

"It is really not safe to mix caffeine with alcohol simultaneously," says Dr. Wakim-Fleming. "There is no study that says this is safe." What's more, the U.S. Food and Drug Administration considers caffeine an "unsafe food additive" in alcoholic beverages, and in 2010, it warned the manufacturers of seven caffeinated alcoholic beverages that they couldn't be sold in their current form, as they weren't generally recognized as safe.

Negative Health Effects of Consuming Caffeine and Alcohol Together

Mixing caffeine and alcohol could have short- and long-term negative health effects. ICYDK, alcohol is a central nervous system depressant, which causes sedation and drowsiness by increasing the amount of a neuromodulator called adenosine (which slows down neural activity) in the brain, according to information published in the Journal of Caffeine Research. Caffeine, on the other hand, is a central nervous system stimulant, and it makes you feel energized and awake by blocking adenosine from binding to itsreceptors, research shows. Both substances also affect your cardiovascular system: Caffeine increases your blood pressure and heart rate shortly after consumption, while alcohol may temporarily raise your blood pressure while binge drinking (consuming more than four drinks in a sitting for women or five drinks for men) and your blood alcohol content is rising.

By consuming both substances simultaneously, the stimulating effects of the caffeine can mask the sedative effects of alcohol — potentially leading you to drink more booze, beer, or wine than you otherwise would. "When [the drinker] feels more alert and has an increase in their reflexes and reaction time, they feel like they're great and could drink more," says Dr. Wakim-Fleming. In fact, a 2014 study found that 15- to 23-year-old drinkers who mixed alcohol with energy drinks (which, of course, contain caffeine) were four times more likely to binge drink at a high intensity (re: consume six or more drinks quickly) than those who didn't mix the two ingredients. (

And engaging in binge drinking can have immediate side effects on your gut, says Dr. Wakim-Fleming. "Sometimes it delays stomach emptying, causes inflammation in the stomach (aka gastritis), and can lead to nausea, vomiting, or abdominal pain," she explains. Other short-term health risks of binge drinking include sustaining unintentional injuries (by way of car crashes or falls) and suffering alcohol poisoning, according to the Centers for Disease Control and Prevention (CDC).

Since both caffeine and alcohol can raise blood pressure, mixing the two substances may be particularly risky for folks who have cardiovascular disease or other heart conditions, says Dr. Wakim-Fleming. "High blood pressure does not have symptoms — it doesn't give you a warning," she explains. "So if the blood pressure rises, you may not even know it...and you may end up with heart attack or stroke." Even if you don't currently have any heart concerns, repeated binge drinking can lead to long-term increases in blood pressure, which itself increases the risk of heart attack, stroke, and heart failure when left unchecked, according to the Mayo Clinic.

The Takeaway On Caffeine and Alcohol

Again, it generally isn't considered safe to mix caffeine and alcohol, given the potential health risks and increased likelihood of binge drinking. That said, "if you're [combining caffeine and alcohol] once in a while, one glass here and there, it may not have an effect except if you have heart problems," which is why it's so important to know your medical history, says Dr. Wakim-Fleming.

Even if you're not literally mixing caffeine and alcohol in one glass, but rather drinking them back-to-back (think an espresso shot at the end of a meal where you shared a bottle of wine), you'll still want to be mindful. Liquids generally take an hour to empty from the stomach, and the levels of both alcohol and caffeine reach their peak in the blood one to two hours after consumption. Consequently, caffeine's side effects could mask those of alcohol if you consume both within a 60-minute period, says Dr. Wakim-Fleming. That means if you sipped a cup of coffee right before heading to the bar, you'll want to wait at least an hour or two before having an alcoholic beverage. "The more time you have between those two substances, the better," says Dr. Wakim-Fleming.

And if you really want to imbibe in an espresso martini or Irish coffee at happy hour, remember, there's always decaf.

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