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The Science of Hangovers

Maybe this will make it stop

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Sometimes it seems the misery of a hangover is a cosmic joke, a punishment for enjoying a night out. Whatever the reason, you drink a little too much and wake up with a pounding headache, a churning stomach, and the vow to never booze it that hard again. You’re probably lying though. Your next hangover is just around the corner.

There is no consistent rhyme or reason as to who will wake up feeling like death warmed over. But some studies indicate that a blood alcohol content (BAC) of .1 seems to be the magic number. For men, five to seven cocktails over a four to six hour period almost invariably leads to a hangover. Women tend to have the same result after three to five drinks. The symptoms of a hangover will peak when your BAC goes back to zero, around 12 hours after your drink.

Why does alcohol cause a hangover?

The symptoms of a hangover will peak when your BAC goes back to zero, around 12 hours after your drink.

Despite the fact that hangovers are an incredibly common condition, affecting millions of people and responsible for billions of dollars in lost productivity and absenteeism each year, there is a notable lack of studies into their cause and treatment. So the truth is, we’re not quite sure what causes a hangover. But there are a few theories.

In the liver, alcohol is broken down into toxic acetaldehyde. An enzyme, alcohol dehydrogenase, further metabolizes it into harmless acetic acid. If the amount of alcohol you drink outpaces the ability of your enzymes to process it, acetaldehyde builds up in your body, leading to headaches and nausea. A reduced ability to break down acetaldehyde is partially responsible for the "Asian glow"—when some become flushed after drinking.

Another popular theory is cogeners. These compounds, produced during fermentation, exist to varying degrees in different types of alcohol. Dark alcohols high in cogeners (red wine, whiskey, tequila) are shown to increase the frequency and severity of hangovers, as compared to drinks with low cogener content (vodka, gin, rum).

A relative newcomer to the debate is the role of the immune system. A 2003 study found that people with hangovers have elevated cytokines—chemicals secreted by our immune system that work in cell signaling and help to fight off infections. High levels of cytokines have been associated with nausea, headaches, and fatigue and, in some studies, disrupted memory formation.

While more studies are needed to pinpoint hangover causes, we do have biological explanations for some symptoms.

The Pounding Headache

Alcohol suppresses vasopressins, an antidiuretic hormone (the chemical that usually helps you to conserve fluids). That’s why you constantly need to pee. It’s not surprising that a theory arose suggesting dehydration causes hangovers, but science disagrees. Studies have shown that the level of electrolytes in those with a hangover versus those without are not all that different. And further, in cases where there are variances, no correlation exists between severity of symptoms and level of electrolytes or the level of hormones in the blood.

It’s not surprising that a theory arose suggesting dehydration causes hangovers, but science disagrees.

Dehydration may be related to your headache, though. When you’re dried out, the blood vessels in your body narrow, trying to keep your blood pressure up. This has the unfortunate side effect of decreasing blood flow to the brain and dilating the vessels in the brain. Your brain shrinks, pulling away from the skull and triggering pain sensors leading to a headache. This dehydration is also responsible for dry mouth.

The Waves of Nausea

Alcohol irritates your stomach lining and increases production of gastric acid, pancreatic and intestinal secretions. This can lead to nausea, stomach pain, and diarrhea. Despite the urge to vomit, it’s not actually going to help the hangover—the alcohol is already in your blood, so there’s nothing to do but let it run its course.

The Soul-Crushing Exhaustion

Alcohol also inhibits glutamine, a natural stimulant. When you stop drinking the body revs up its production, stimulating the brain and keeping drunkards from a deep and restful sleep. This may be partially responsible for the fact that your body feels like lead and all you want to do is crawl back under the covers and watch crappy television until the misery passes. Also, alcohol consumption can cause a decrease in blood sugar, contributing to fatigue, moodiness, and shakiness.

Can I prevent a hangover?

The only surefire way to prevent a hangover is not to drink, or to drink in moderation. But there are two commonly touted prevention tricks ...

Eat Something

Here, eat some bread, it will soak up the alcohol. The logic here is flawed—using half a loaf of Wonder Bread as a sponge is not going to leech the alcohol from your blood—but the method is sound ... if you eat before you drink. When you eat a large meal, the valve in your stomach closes, keeping your food (and booze) in the stomach to be digested slowly rather than pouring it right into the small intestine. This is especially true of fatty and protein laden foods, both of which take time to digest. If this valve is closed before you start drinking, the alcohol will hit your body more slowly.

Don’t Mix Drinks

... there is some evidence that mixing drinks with different levels of cogeners can lead to particularly brutal hangovers.

Liquor before beer, you’re in the clear … is one of the poems most Americans know by heart. It’s not entirely true—regardless the order you drink, you’re putting the same amount of alcohol into your body and you will feel the effects whether you stick to the poetry lesson or not. On the other hand, there is some evidence that mixing drinks with different levels of cogeners can lead to particularly brutal hangovers. Additionally, carbonation is known to increase the blood’s absorption of alcohol. Drinking carbonated beverages (including beer) before or with hard liquor may cause more rapid absorption, getting you drunk faster.

How to treat a hangover

A 2005 study in the British Medical Journal found no evidence for the effectiveness of any popular hangover treatments. It concluded with the rather obvious assessment that "The most effective way to avoid the symptoms of alcohol induced hangover is to practise abstinence or moderation." However most college students disagree with the research, offering their own ways of battling the alcohol-induced doldrums.

Hair of the Dog

This expression dates back over a century and refers to the technique of treating a rabid dog bite with a piece of the dog’s hair. As a curative treatment, it makes about as much sense for rabies as it does for treating a hangover. It may make you feel better temporarily, but it is only making you numb to the hangover. It’s still going to hit you eventually—you’re just dragging it out.


Another popular treatment is taking aspirin. There is some logic to this—a possible culprit in hangovers is your immune system, and aspirin, a nonsteroidal anti-inflammatory, can target some of the chemicals involved in making you feel terrible. Studies have shown that a similar drug, Tolfenamic acid, is effective in reducing hangover symptoms, but this drug is not available in the U.S.

Photos via Shutterstock/Lisa S., Shutterstock/successo images.

Taken before bed, aspirin may help reduce the effects of alcohol on the immune system. Taken in the morning, you may benefit from the painkilling properties as well. Two things to note:

  1. Aspirin can increase the risk of stomach bleeding so take with caution.
  2. Do not take Tylenol to treat a hangover. Tylenol is processed by the liver— that organ you just overloaded with booze. Give it a rest.


This is important. Any fluid, really. Gatorade, chicken soup, tea. Although dehydration is not responsible for your hangover, it is related to some of the symptoms. Rehydrating is key to bouncing back. Eating a banana may help restore some of the potassium lost.

Studies have shown that a similar drug, Tolfenamic acid, is effective in reducing hangover symptoms, but this drug is not available in the U.S.

Burnt Toast

Activated charcoal is commonly used to treat certain types of poisoning. Since burnt toast contains carbon, a component of charcoal, some have made the assumption that it will be effective in treating hangovers. In truth, charcoal is not used for treating alcohol poisoning though, and certainly not for a hangover. You’re better off eating the much more palatable alternative: appropriately toasted toast.


Like alcohol, coffee is a diuretic and will further dehydrate you. As a stimulant, caffeine may give you a jolt and temporarily help with the headache, but it won’t cure the hangover.

Greasy Food

Eating a large meal serves you best when done before a night of drinking. Eggs may help though. They are high in cysteine, which can help the body to increase the function of a substance called glutathione, a key element in breaking down acetaldehyde. So an egg sandwich could offset that hangover.

Final words of wisdom: moderate your intake, have a sober (ish) buddy, and do not drink and drive.


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