Many people drink coffee when they have a hangover. But coffee does not cure a hangover. Caffeine can make you feel more awake, but it does not help your body break down alcohol faster. Your liver breaks down alcohol at an almost fixed speed.

Scientists looked at many studies, but no remedy clearly worked. An American institute says only time cures a hangover. The best way is not to drink too much.

After a night of heavy drinking, many people reach for a cup of coffee. But according to the U.S. National Institute on Alcohol Abuse and Alcoholism, neither coffee nor a shower can cure a hangover. Only time can. A hangover has several causes.

Poor sleep, mild dehydration and substances made when the body breaks down alcohol all play a part. Caffeine can make you less sleepy, but it does not help the liver process alcohol any faster. A 2005 review of randomized trials found no convincing evidence that any hangover remedy works.

So why do some people feel better after coffee? Regular coffee drinkers may get headaches when they miss their usual caffeine, and a cup takes that headache away. The hangover itself is still there.

Coffee is a favorite morning-after remedy, yet the U.S. National Institute on Alcohol Abuse and Alcoholism states plainly that neither coffee nor a shower cures a hangover; only time does. Part of the difficulty is that a hangover has several causes at once: disturbed sleep, mild dehydration from increased urination, the effects of acetaldehyde and other breakdown products, and stomach irritation or inflammation-like responses.

Caffeine addresses none of these directly. Alcohol is metabolized mainly by the liver at a fairly constant rate, and caffeine does not accelerate it; it merely reduces sleepiness, which can create a false impression of being sober.

Researchers warn that combining alcohol and caffeine while drinking may lead people to underestimate how drunk they are. Systematic reviews support this picture. A 2005 review of randomized controlled trials found no convincing evidence for any hangover treatment, and a 2022 review concluded that the evidence for various substances was of very low quality. Why, then, do some people feel better after coffee? For habitual drinkers, caffeine relieves withdrawal headaches, which can be mistaken for relief from the hangover itself.