"I'll never drink again." It's a claim many of us have made the morning after a debauched night while struggling to face the daylight with a pounding headache, a parched tongue and a distinctly queasy feeling in the pit of the stomach.

For many, this promise is short-lived and is particularly hard to maintain during the holiday season. As Robert Swift, MD, a professor of psychiatry at Brown University Medical School and associate chief of research at the Providence VA Medical Center in Rhode Island, points out, people tend to increase their alcohol consumption during the holidays when there are more parties and people have more leisure time.

So if you've overindulged at the office holiday party, you might find yourself not only deeply embarrassed but also seeking a quick hangover cure. Hangover remedies abound and include such treats as anchovies, tea made from rabbit droppings and, of course, another stiff drink. But do any of them work? Below, Dr. Swift talks about what exactly causes a hangover, how best to cope—and how to avoid such misery in the first place.

What is hangover?
Hangover is a "collection" of symptoms that occur after a bout of alcohol drinking. It's that simple.

What predisposes some people to hangover?
There are some studies that suggest that there may be some genetic predispositions to hangover, although that's not clear. Obviously, larger quantities of alcohol are more likely to produce more severe hangovers. And there are a lot of other factors that may go into it as well. There is some evidence that the type of alcohol consumed may relate to hangover, the time of day that the alcohol's consumed, whether one is drinking instead of sleeping, whether you eat while you're drinking, and how well hydrated you are.

Can you give a sense of how many drinks are needed over what period of time for an average person to end up with a hangover?
That's hard to know because it depends on a lot of factors, and it's an individual sort of thing. There are people who are drink very, very heavily—who are alcoholics—and never get a hangover and there are some who drink very heavily and they do get hangovers

What the worse time of day to drink in terms of hangover?
It's interesting. On the one hand, alcohol consumed in the morning tends to be more intoxicating, believe it or not. But by and large, most people drink in the evening and late at night, and that means that they may be drinking instead of sleeping and alcohol influences the quality of sleep as well. As a result, one ends up sleep deprived, and that can certainly exacerbate hangover symptoms.

Does body weight play a role?
Body weight will play a role in that it affects the concentration of alcohol and other substances that ultimately get into your body. The concentration is actually affected by the amount of water in your body, which is partially dependent upon your weight but not entirely. When people do calculations of alcohol—how much alcohol will it take to achieve to a certain blood alcohol level—they look at what's called "lean body weight" because the alcohol doesn't go into the fat. So a fat person isn't necessarily more resistant to the effect of alcohol because they may have the same amount of body water as somebody who's very skinny.

Men have more body water than women do, so if a man and a woman who weigh the same drink the same quantity, the man will have a lower blood alcohol than the woman will, because the woman has less body water to dissolve the alcohol.

What are some of the symptoms of hangover?
I think the predominant symptom of hangover is headache. Most people experience a headache, and many experience some gastrointestinal symptoms, predominantly nausea and sometimes vomiting. There's a sense of general malaise, of just not feeling well, feeling like you're fatigued, can't concentrate. People's mouths feel very dry because they're dehydrated.

What is happening in the body to cause these symptoms?
That's still not entirely known. There are two major theories about the causes of hangover. The first theory is the withdrawal theory, which suggests that hangover is really a type of mild alcohol withdrawal. If you look at people's brains in a brain wave machine, even though people may be feeling fatigued and tired, their brain is actually stimulated. And that's what alcohol withdrawal is: It's a hyperstimulatory state. Chronic alcoholics, if they stop drinking, get anxious, they get excited, they can't sleep, they get the shakes. They may even hallucinate. It's thought that even one bout of heavy drinking may induce a state of kind of mild central nervous system excitation and people perceive that as a hangover.

The second theory is that the hangover is due not to the alcohol per se but other things in the alcohol, the so-called congeners. A beverage alcohol is usually not 100 percent pure. For example, whiskey may be distilled, but then it's stored in charred-oak barrels for years and years, so you get all of these compounds that leach out of the barrels and then get degraded over time. There are hundreds of biological compounds in alcohol beverages. Of course, with wine and beer, you actually add yeast to the grapes or the malted barley or whatever, so there are lots of chemicals in it.

The other thing is that the yeast also makes other kinds of alcohols. When yeast ferments sugar and alcohol, the vast majority of what it makes is ethyl alcohol, which is the alcohol we drink. But the yeast can also produce other alcohols, such as smaller alcohols like methanol (or wood alcohol), and methanol's pretty toxic. It can cause blindness, in fact, if you drink it pure.

When methanol is metabolized in the liver, it's converted to formaldehyde, which is embalming fluid. So when you drink alcohol that contains some methanol, your body first gets rid of the ethyl alcohol but the methanol stays in your blood. It doesn't get degraded, and it actually builds up over time. Then when you've burned up all the ethanol, you start to metabolize the methanol and produce formaldehyde as a byproduct of that, and some people feel that produces the symptoms.

Do certain types of alcohol beverages have more methanol than others?
Yes. There appears to be a relationship between the likelihood of getting a hangover and how dark the alcohol is. The color means that the alcohol has more junk in it. The darker color is somehow reflecting the level of congeners. So more clear-colored alcohols, like vodka and gin, are less likely to give you a hangover than a darker-colored alcohol, like a whiskey or a scotch, bourbon or brandy. Likewise, among wines, people often find they're more likely to get a headache from red wine rather than white wine. Sulfites in red wine may contribute to hangover in people who are sensitive to them.

How can people treat a hangover?
Prevention is best. Avoid alcohol and you won't get a hangover. Drinking in moderation will also help. Mixing alcohol with other beverages, drinking slowly. Drinking alcohol with food will reduce the concentration of alcohol in your stomach. It will dilute it and be less irritating to the stomach. Also when people drink and eat at the same time, less alcohol is absorbed into their blood because the alcohol's absorbed more slowly and therefore more of it gets metabolized by the liver and the stomach before it gets into the blood stream.

Why do some people argue that a drink in the morning cures hangover?
The "hair of the dog that bit you"—a drink in the morning—might make you feel better because you stop the metabolism of methanol and the formation of formaldehyde because you've got alcohol in your system again. That could help the withdrawal theory, too. If you are withdrawing from alcohol, so to speak, you give yourself a little bit of alcohol to "detox" yourself.

If you have overindulged, are there any options?
If you have overindulged, remedies abound. I think for thousands of years probably there have been reported remedies for hangover. But there really is very little that has been scientifically proven to improve a hangover. In fact, I don't know of anything.

So people should just treat their symptoms?
People should treat their symptoms, but even treating the symptoms can have side effects. For example, if you have a headache, you can take an antiinflammatory medication like aspirin or ibuprofen. But, those can be irritating to the stomach, which has already been irritated from the night before. And after you've been drinking a lot of alcohol, you should not take acetaminophen (Tylenol) because it has some toxicity to the liver, which is actually magnified by drinking alcohol. In fact, there have been questions about whether there ought to be a warning on the label.

Rehydrating will help, though people aren't as dehydrated as much as they feel dry. But actually drinking fluids, having some carbohydrate in case your blood sugar's down, having something mild in the stomach if there's some stomach irritation, is a good idea.