Does Coffee Help You Sober Up?

The Effects of Caffeine and Coffee After Drinking Alcohol

Young woman sitting in bed with coffee
Coffee won't make a drunk more sober, but it may make you more awake. Jamie Grill/Getty Images

You may have heard you can drink coffee or take a cold shower to sober up from drinking alcohol, but does it really help? Here is the scientific answer and explanation.

The answer to this question is a qualified "no." Blood alcohol level doesn't diminish, but you might feel more awake from drinking coffee.

Your body takes a certain amount of time to metabolize alcohol. Drinking coffee does not reduce recovery time, which is dependent on the quantity of the enzymes alcohol dehydrogenase and aldehyde dehydrogenase.

You cannot make these enzymes more abundant or more effective by drinking coffee.

However, coffee contains caffeine which acts as a stimulant, while alcohol is a central nervous system depressant. Although you will be intoxicated until your body metabolizes the alcohol, the caffeine can serve to wake you up. So, you're still drunk, but not as sleepy. Worse, judgment remains impaired, so an intoxicated person may feel recovered enough to perform risky tasks, like operating a motorized vehicle.

Caffeine and the Effects of Alcohol Over Time

Caffeine isn't going to make a big difference in how awake you feel early on while drinking. For the first hour and a half after drinking alcohol, blood alcohol levels rise and people actually feel more alert than before. Drinkers don't feel sleepy until 2 to 6 hours after drinking. This is when you're most likely to reach for the coffee as a pick-me-up. Caffeine takes about half an hour to hit your system, so the impact on your wakefulness is delayed, not an immediate reaction to drinking a cup of joe.

As you would expect, decaf isn't going to have much of an effect, one way or the other, except to help replenish fluid lost from the dehydrating effect of alcohol. Caffeine or any stimulant dehydrates you, but full-strength coffee doesn't really worsen the effect from drinking alcohol.

Experiments on Whether Coffee Sobers You Up

Even if your metabolism is faster, experiments have shown that even after several cups of coffee, caffeinated drunks don't fare better than their intoxicated, uncaffeinated counterparts.

There doesn't seem to be any shortage of volunteers willing to drink alcohol and coffee for science, either. The Mythbusters team performed eye-hand coordination tests, had a couple of rounds, performed tasks, and then tested reactions again after several cups of coffee. Their small study indicated coffee did not help eye-hand coordination.

The effects of caffeine on intoxication aren't limited to humans. Danielle Gulick, PhD, now of Dartmouth College, examined how well young adult mice were able to navigate a maze, comparing a group injected with different amounts alcohol and caffeine versus a control group injected with saline. While the drunk and sometimes caffeinated mice moved around more than their sober counterparts and were more relaxed, they did not complete the maze as well. The drunk mice, with or without caffeine, did not exhibit anxious behavior. They explored the maze just fine, but they were not able to figure out how to avoid parts of the maze that had bright lights or loud noises. While the study doesn't say, it's possible the mice simply didn't mind those things while intoxicated. In any case, caffeine did not alter mice behavior, compared with how they acted when exposed to alcohol alone.

The Danger of Drinking Coffee If You're Drunk

One dangerous effect of drinking coffee while intoxicated is that the person under the influence thinks he is more sober than he was pre-coffee. Thomas Gould, Ph.D., of Temple University, published a study in the journal Behavioral Neuroscience that concluded people associate feeling tired with being intoxicated. If they aren't sleepy, they may not recognize they are still intoxicated.

Not all research is so clear-cut. Studies have been conducted on the effect of drinking coffee on the driving ability of intoxicated subjects (no, the drunk drivers weren't out on public roads). Results to date have been mixed. In some cases, coffee seemed to partially reverse the sedative effect of alcohol, leading to an improvement in reaction time. In other tests, coffee did not improve driving performance.

You may also enjoy reading about why coffee makes (some) people poop.

Reference

Liguori A, Robinson JH. Caffeine antagonism of alcohol-induced driving impairment. Drug Alcohol Depend. 2001 Jul 1;63(2):123-9.

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Helmenstine, Anne Marie, Ph.D. "Does Coffee Help You Sober Up?" ThoughtCo, Mar. 25, 2017, thoughtco.com/does-coffee-help-you-sober-up-607365. Helmenstine, Anne Marie, Ph.D. (2017, March 25). Does Coffee Help You Sober Up? Retrieved from https://www.thoughtco.com/does-coffee-help-you-sober-up-607365 Helmenstine, Anne Marie, Ph.D. "Does Coffee Help You Sober Up?" ThoughtCo. https://www.thoughtco.com/does-coffee-help-you-sober-up-607365 (accessed May 21, 2018).