Do not drink plain water. Everyone here is WRONG. Well, not super wrong. Your hangover won't be as bad the next day if you're hydrated properly, true, but all the pissing you do depletes other things including electrolytes, sugar and as someone previous to me said any water soluble vitamins in your system.

What you want to drink is pedialyte. I am dead serious. Or gatorade or a sports drink that replenishes electrolytes and sugar. When I go to concerts I sneak in the new gatorade pouch guys because I drink and dance and sweat.

Also, don't drink cold pedialyte. Drink it near room temp.

If you pick a painkiller, stay away from anything with acetaminophen in it because it's not good for your liver either.

Take a multi-vitamin after you eat.

Eating a big meal (as long as you're not nauseated) helps because you gain all that stuff back when you eat it.

The best thing to do is eat something bready or filling about 2 hours before you crash out, take a multivitamin when you're done puking and drink some pedialyte or gatorade at room temp. Or do whichever of these suits your style of drunkenness best.
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