Why do hangovers occur?

Join Our Community of Science Lovers!

Sant P. Singh, a professor and chief of endocrinology, diabetes and metabolism at the Chicago Medical School, explains.

The alcohol hangover has been known since Biblical times: "Woe unto them that rise up early in the morning, that they may follow strong drink" (Isaiah 5:11).

Approximately 75 percent of those who drink alcohol to intoxication will experience a hangover. Consumption of relatively large amounts of alcohol leads to more severe symptoms, which include headache, nausea, vomiting, thirst and dryness of mouth, tremors, dizziness, fatigue and muscle cramps. Often there is an accompanying slump in occupational, cognitive or visual-spatial skills. Other symptoms, such as tachycardia (rapid heartbeat) and changes in blood pressure, might go unnoticed by the sufferer.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


Although still under debate, the cause and mechanism of a hangover seem to involve several factors. Hangover has been suggested to be an early stage of alcohol withdrawal. Acetaldehyde, a breakdown product of alcohol metabolism, plays a role in producing hangover symptoms. Chemicals formed during alcohol processing and maturation known as congeners increase the frequency and severity of hangover. Liquors such as brandy, wine, tequila, whiskey and other dark liquors containing congeners tend to produce severe hangovers, whereas clear liquors (such as white rum, vodka, and gin) cause hangovers less frequently. Researchers have shown that severe hangover occurred in 33 percent of subjects who ingested bourbon (which is high in congeners) but in only 3 percent of those who consumed the same dose of vodka (which is low in congeners). As a rule of thumb, the darker a liquor's color, the more congeners it contains.

Patients with hangovers show changes in the blood levels of several hormones, which are often responsible for some of the hangover symptoms. For example, alcohol inhibits antidiuretic hormone, which leads to excessive urination and dehydration. Dehydration accentuates the symptoms of a hangover. Other factors that contribute to an alcohol hangover include consumption of larger quantities of alcohol than the person can tolerate. Individuals who drink alcohol rapidly, or without food, or without diluting it with nonalcoholic beverages, are more prone to developing a hangover. Mixing different alcoholic drinks can also cause a hangover. Additionally, smoking, loud music, flashing lights and decreased quality and quantity of sleep can exacerbate hangover headaches.

One can diminish the severity of the hangover by paying attention to the amount and type of alcohol consumed, as well as controlling other factors mentioned above. It is not clear that sugar-containing foods ease hangover symptoms, but sugar and fluids can help overcome hypoglycemia and dehydration, and antacids can help alleviate nausea. To reduce headache, anti-inflammatory drugs should be used cautiously. Aspirin may irritate the stomach and alcohol can amplify the toxic effects of acetaminophen on the liver. Other drugs have been used to treat hangovers, but most have questionable value. Propranolol, a beta blocker drug, has no beneficial effect on the symptoms of hangover. Tolfenamic acid, a prostaglandin inhibitor, produces some improvement in hangover symptoms when given prophylactically. The psychotropic sedative chlormethiazole has been reported to reduce symptoms of hangover, as have vitamin B6 and an herbal preparation called Liv.52 made by the Himalaya Drug Co. in Bombay, India.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe