We've all felt it It is what we accept as fact, part and parcel of our louche existence, the undeniable, cleansing truth...

It is the Faustian bargain we make every time we knock back another triple Jameson, every time we empty another few pints. It is a revenge that would make Montezuma hide under a pile of cocoa leaves. It is the biggest turnaround since Benedict Arnold. It is a full-time synonym, attached to all manner of post-celebratory excess, applicable to riots and recovering economies alike.

It is that peculiar feeling that your stomach is trying to exit your body via the mouth. It is, unmistakably and aptly, a hangover. One minute, you're on top of the world. Life of the party, or at the very least, seated on a comfortable stool. The next, you're waking up in a frenzy, fully dressed, maybe on a lawn, maybe in your car, more likely on the kitchen floor, a taste rising in your throat like bile, familiar bile.

Hangovers, unlike the all-too-short experience which precedes them, are long, complicated matters, thought about by some of America's most eminent smart people, people with capital letters after their names and cushy positions in the field of Academe. It will take some doing just to explain what, exactly, happens to your body The Morning After, much less tell you how to fix it. So let's start with the facts.

Problem: You were drunk. Admit it. You were all over the place, kissing strangers and knocking over tables. That's probably how you cut your hand. You might have thought about that in advance, you know, because the only fer-sure hangover cure in the world is - drum roll, Maestro, for the kids watching TV - abstinence. Yup. Horrible, awful, abstinence. We here at BarmanGuide know better than to advocate such silliness.

If we did, the staff at Modern Drunkard might kick ass en masse, and we know better than to enrage our fellow barflies. So we will leave abstinence where it most deservedly belongs - in history's septic tank, sloshing around with animal sacrifice and The Hustle. On to the next fact. Unless you are one of those people - we're looking at one Ryan McAndrews here (you'll find him anyplace red-blooded Americans drink cheap booze and cuss) - who don't generally get the traditional hangover, this is where it gets ugly. You feel bad, very bad. Your head hurts. You feel like vomiting. You vomit and you still feel like vomiting.

Oh, Nelly. How could something that makes you feel so good make you feel so bad? In a word, dehydration. Here's where we turn it over to the smart people for a minute. According to Michelle Hansen, R. D., corporate dietitian for Albertson's Supermarkets, alcohol "inhibits the formation of ADH, or antidiuretic hormone. Even though you are consuming massive quantities of liquid, your body is programmed to eliminate more than it's taking in."

That, we suppose, is the academic way of saying that drinking too much dries you out. Dehydration is public enemy number one in hangover world. A slightly less obtuse definition has been provided by the good folks at thevirtualbar.com, where all things alcohol are sacred - so sacred, in fact, that the sops haven't gotten around to updating their page since last year - and definitions for the condition we know of as hangover are provided with a flourish:

"Alcohol is a diuretic which is another way of saying it makes you pee.Basically, removal of toxins from the bloodstream is a water-intensive process. It is not exactly the chemical process of treating the alcohol that uses the water (as someone else said), but rather the fact that the toxins are carried across the membranes in the kidneys dissolved in lots of water. So it is the direct removal of ethanol that can lead to the dehydration."

So in the process of washing out all of that pesky ethanol that made you all loopy and foolish, your body used up all of its H20 stash. Bummer. That leaves you, my friend, back next to the toilet, more well-rounded perhaps for the knowledge that you are dehydrated, but no less equipped to deal with it. Patience. We haven't even reached ADH or ALDH, or even congeners.

Huh? We'll start with congeners. Congener is a fancy science-type name for any of the various impurities in alcohol, free-floating products of distillation and fermentation that, in quantity, serve not only to impart flavor but also to aggravate the misery of The Morning After. Congeners are generally found in darker, sweeter liquors - bourbons, dark whiskeys. But their effect, while significant, is minor when compared to that of two alcohol-breaking enzymes in your own body.

Now, as simply as possible - and simply enough that we here can understand - an explication of the purpose of these two substances: Alcohol Dehydrogenase, or ADH, converts ethanol to something called acetaldehyde. Aldehyde Dehydrogenase, or ALDH, converts acetaldehyde to acetate. While acetate is harmless, acetaldehyde (similar to formaldehyde, which anyone who ever took junior high biology knows by smell) is not.

An individual's relative concentration and balance of these two enzymes goes a long way to determining their respective tolerance; some peoples, most notably Native Americans, possess a higher frequency of slow ALDH and fast ADH. In combination this can contribute to a much more severe alcoholic reaction. Depending on your particular genetic makeup, that throbbing feeling in your head is largely attributable to these two substances.

So you should have kept away from all of those Island Punches and glasses of red wine. Unfair, too - after all, it's not like you got a chance to decide your ADH/ ALDH balance. It just is, like having blue eyes or a tendency to wash your hands a lot. So if you, like our Mr. McAndrews, are lucky enough to have a favorable balance, good. Enjoy it. You don't need to read any farther.

The rest of you listen up: The scientific stuff only goes so far. Knowing why you feel bad isn't necessarily a great comfort. It's time to move on to feeling a little bit better.

Solutions: Ah, hangover cures. Every culture and subculture has them in spades. Ask a Mexican national what you should do after a night of mucho pinche cerveza, and he'll point you in the direction of the nearest bowl of menudo. Ayurvedic doctors, who are most likely nice people (although you probably wouldn't trust them to set your broken leg or pull a lead slug out of your lung), recommend drinking a concoction of lime, cumin and orange juice.

There are some among the hardcore drinkers of the world, many of them gainfully employed in the landscape or construction industries, who believe that nothing wipes out a hangover like a beer and a cup of black coffee together. One piece of internet advice exhorts the hung to eat a big breakfast, then go and puke it up immediately.

All of this, of course, suggests that no one really has a magic bullet when it comes to curing the hangover. But there are a few genuinely effective methods, one of which is rooted in a bit of old wisdom that holds tomatoes to be unmatched in their curative properties, as well as proving true the oldest piece of hangover wisdom there is - that you need "a little hair of the dog that bit you."

Which brings us, naturally, to the Bloody Mary.

This ought to make you want to get up from that toilet. Nothing - nothing - makes a recovering sad sack feel better than this famous tomato juice-Worcestershire sauce-vodka- lemon juice-Tabasco-whatever combo. Garnished with something tall and green, punched up with horseradish, loaded to the nipples with delicious potato water, this is the alcohol to make you forget about that alcohol. Don't waste your time with beer and coffee. Don't eat just to puke. Don't sprinkle anything with cumin, no matter what. This is your little helper right here.

If you don't subscribe to the theory that a little liquor'll heal you quicker, then read on. There are a variety of tasty alternatives, though none of them has ever proved to be anything beyond anecdotally effective (not like a Bloody Mary, mind you, which always works). The Romans, for instance, ate fried canaries. You could try one of those, although I doubt you'd be able to outrun the hordes of animal rights activists who would most likely chase you into an abandoned building and beat you to death.

Instead, you might look to the hippies for inspiration. It turns out that vitamins might actually be useful for something besides fortifying Sugar Smacks. Try some vitamin B and wheatgrass, as antioxidants help the body recover from the damage that alcohol can inflict on cells. Niacin also helps by pushing the alcohol through your body more quickly. Juices are generally a good choice for re-energizing as well, but the hands-down prize for curing dehydration is the Ancient Mariner's nemesis, landlord of most of the planet and home to a whole bunch of fish, good ol' water.

But you probably didn't need us to tell you that. After all, when you're hunched over the bathroom trash can, do you really want a double caramel latte? Of course, here are other ways. You could drink your own urine, which is said to be the be-all, end-all of hangover cures in parts of India. You could meditate, or pray. You could hit yourself in the head with a board until you achieve a state of religious ecstasy. And you could always fry up a canary or two, as we already mentioned.

But whatever you do, avoid taking Tylenol or acetominophen, which can damage your liver and kidneys something fierce. Actually, drunks like us should avoid these substances even when we are at our most normal - here's what the smart people at the University of Pennsylvania school of medicine had to say:

"Acetominophen, aspirin and ibuprofen should never be taken with alcohol (unless directed by a physician).Alcoholics should even avoid them when not drinking. These drugs are metabolized by the liver and if the liver has upregulated p450 enzyme system it releases a toxic metabolite. Alcohol plus acetominophen has led to numerous liver transplants and is very dangerous."

Uh, okay. We'll take that to mean that you shouldn't gulp aspirin or Tylenol or anything else when you're hung over or, for that matter, at any other time. This is why you read BarmanGuide - factual information that can change your life. You were just about to choke down a couple of those beauties, weren't you? Well, if you can keep something down - even Bloody Marys do, unfortunately, tend to vacate the premises quickly if unaccompanied by a few eggs - that must mean you're feeling a little better.

The pain of a hangover is retribution, the comeuppance. Nothing is free in this dirty little world, least of all the blissful, mentally unencumbered high of a solid drunk. It'll empty your wallet and your stomach. So this holiday season, be prepared. Keep your B-complex and vodka at the ready. Drink wheatgrass juice and water.

Or try the bartender's choice - some ice cream. Will it cure your hangover? Who cares? Who's ever sorry they had ice cream?