All the weeks leading up were just practice. This is the real deal - St. Patrick's Day weekend. But the wearing of the green doesn't need to extend to your complexion. And even the most determined merrymakers shouldn't depend on the luck of the Irish to to have a memory-worthy holiday celebration.

It should go without saying that nobody should ever drive after drinking. If you indulge, take a bus, train, cab, Uber – just don't get behind the wheel.

And if you're at all health-minded,  before embarking on a day-into-night drinkfest, you might want to consider exactly why the morning after never feels as fun as the night of.

"Alcohol puts the toxic in intoxication," said Aaron White, senior scientific adviser with the National Institute on Alcohol Abuse and Alcoholism. As with any toxic substance, alcohol sends your immune system into overdrive, accounting for that lousy, hung-over feeling, according to the Mayo Clinic.

"The next day, you feel this malaise," White said. "In effect, you've poisoned yourself."

There is nothing like abstinence, though moderation takes a close second. With that in mind, we asked White how revelers can best survive this buzz saw.

First of all, forget anything you have seen about hangover preventions like Pedialyte. Nothing will prevent a hangover if you drink too much. End of story.

But there are some smart ways to pace yourself.

  • Before you indulge, have a meal, advised White. Those old posters you see in Irish bars about Guinness being good for you may have been good for sales back in the day, but what your body needs is ballast.

One of the first things alcohol does is irritate your stomach. That's one reason public vomiting is one of the less cherished parts of the Erin Express. Food acts as a bit of a buffer and can slow the absorption of alcohol.

Just know that if you drink too much, no meal, whatever the grease content, will save you.

  • Another wise move is to drink nonalcoholic fluids and plenty of them. Alternate nonalcoholic beverages with the alcoholic ones.  Alcohol makes your body produce more urine, which dehydrates you, contributing to the next day's hangover.

Consuming healthy fluids also helps dilute the alcohol and its effects on your body. As White said, "all of your organs and tissues get bathed in alcohol."

  • Keep track of how much you are drinking. Alcohol can disrupt frontal lobe activity, impairing judgment. It can also suppress the part of the brain that deters us from risk-taking.

Drink enough, and you can even shut down breathing and gagging, which are  governed by the brain stem -- and essential for life.

With a blood-alcohol content of 0.35 percent -- that's about 11 drinks in four hours for a 130-pound woman; 16 drinks for a 160-pound man -- a drinker has a 50-50 chance of death from fatal brain stem suppression, White said.

  • Don't mix alcohol with other substances. More than 22 percent of all opioid overdoses involve alcohol, White added.

If despite your best efforts at behaving yourself, you end up with a pounding head — because alcohol does make your blood vessels expand — avoid acetaminophen.  That and the alcohol make a harmful combination for your liver.

Alcohol is a famous sleep disrupter, so you will likely be very tired the next day, on top of everything else. But the old so-called cure of another drink just postpones the inevitable.

"The hair of the dog may help for a little while," White acknowledged. "But you're only delaying the misery."