Alcohol is considered a poison and characters are allowed to consume 1+ (2x Con Score) in drinks without having to make a saving roll or becoming sickened for one hour per drink that exceeds this limit. There are no rules for a drinking contest. This article will attempt to address that issue.
The saving roll for alcohol is a Fort save; an alchemist’s and investigator’s bonus to saving rolls vs. poisons do apply, as would any other character feature that provides a saving roll bonus vs. poison. All dwarves get a +2 to save vs. alcohol poisoning, due to it being so prevalent in their culture. Halflings have a legendary capacity for food and gain a +1 bonus to their Fort saves vs. alcohol poisoning. Any character that is immune to poison cannot be made sickened or drunk by alcohol use. Drinking on an empty stomach saddles the character with a -2 modifier to the number of drinks they can consume each day.
A character who exceeds their capacity for alcohol is drunk, unless they pass a Fort save. The Fort save is based on the class of alcohol and there is a cumulative +1 to the DC modifier for each drink taken after becoming drunk. A character who has exceeded the amount of drinks they may take in one 24-hour period who passes their Fort save can stave off the Sickened condition, however they suffer a -2 to Wis and Dex scores for one hour per drink that exceeds the maximum daily limit. This penalty is cumulative for every 4 extra drinks taken beyond the daily limit.
The following effects can change the onset of drunkenness. Throwing up can reset the number of daily drinks by 1d4+1, the DM will keep this number secret, so the drinker will not know. The spells neutralize poison totally rids the body of alcohol. The spell delay poison delays the drunkenness and the Sickened condition until the spell wears off.
From Wikipedia: https://en.wikipedia.org/wiki/Alcoholic_drink
Alcohol Type Size of Drink Alcohol Class Fort DC
Fermented Drinks; Ale, Apple Wine, Beer, Cider, Mead 10-20 ounces Light 10
Fermented Drinks; Sparkling Wine, Wine Cooler 10-20 ounces Light 12
Catalan, Cava, Champagne, Honey Water, Sake, Wine 5-15 ounces Light 13
Applejack, Commandaria, Fortified Wine, Madeira, Marsala, 5-10 ounces Medium 14
Prosecco, Port, Sherry, Vermouth
Distilled drinks; Brandy, Gin, Tequila, Vodka 4-10 ounces Medium 15
Rectified drinks; Whiskey 2-6 ounces Strong 16
Distilled and Concentrated; Ever Clear, Moonshine 4-6 ounces Strong 18
Magically Concentrated; anvil and dwarf dropper 4-6 ounces Very Strong 20
If you cannot find the type of alcohol offered, then consult with your DM and pick one that is approximately like the type of alcohol ingested. Mixing drinks can cause you problems; “drinking beer than liquor makes you sicker quicker.” So, drinking a light grade alcohol followed by a medium or strong alcohol gives the drinker a -1 modifier to their saving roll for each pair of light and medium or stronger drinks that they take.
Ale is a type of beer made without hops and typically has 6-18 proof.
Anvil is a brewed alcohol it is a magically concentrated alcohol of 230 proof (that is 115% alcohol) Apple Wine is made from fermented apples and typically 15-20 proof.
Applejack is made from fermented apple wine that is frozen to distill it further increasing the alcohol content to 20-30 proof.
Baijiu is a distilled drink typically 60-110 proof.
Beer is made from fermented grain mash and various grains, flavored with hops typically 6-18 proof.
Brandy is distilled wine. Typically; 70-120 proof.
Catalan is a wine made from a certain region and trademarked it can have 18-32 proof.
Champagne is a type of sparkling water grown in a special region and trademarked and is typically 15-35 proof.
Cider is made from fermented fruits typically 17 proof.
Commandaria is a desert wine, made from a certain region and trademarked with 30-40 proof.
Dwarf Dropper is a distilled, refined and magically condensed drink that is 275 proof (137% alcohol by volume).
Ever Clear; is a distilled and refined alcohol that is clear colored with a proof value ranging from 180-195 proof.
Fortified Wine is wine that is further processed in increase the alcohol content to 20-40 proof.
"Fruit wines" are made from fruits other than grapes, such as plums, cherries, or apples; typically, 18-32 proof.
Gin is produced from fermented juniper berries. Typically; 75-100 proof.
Honey Water and Tequila are made from fermented cactus; typically, 60-110 proof.
Liqueurs, Mixed drinks, and Tinctures are rectified alcohol created by distilling and redistilling alcohol. Typically, 190-220 proof.
Madeira is a fortified wine made in a region and is trademarked it typically has a proof of 20-40.
Marsala is a fortified wine made in a region and is trademarked it typically has a proof of 20-40.
Mead is made from fermented honey typically 16 to 40 proof.
Moonshine is fermented and then distilled alcohol with 180-195 proof.
Port is a fortified wine native to a certain region and trademarked with a proof value of 40-65.
Prosecco us a sparkling wine or semi sparkling wine often known as a still wine with a proof value of 20-30.
Sake is made from fermented rice; typically, 18-32 proof.
Sherry is a fortified wine made with white grapes and has a 20-40 proof.
Sparkling Wine and Champagne are made from fermented grapes and given a secondary fermentation to produce the carbonation, typically 15-35 proof.
Soju is a distilled drink typically 60-100 proof.
Tequila is a distilled drink made from the blue agave cactus plant grown in desert areas.
Vermouth is a fortified wine that contains sugar; dry vermouth has less than 4% sugar, while normal vermouth has 5%-10% sugar with a proof content of 32-36.
Vodka is a mostly clear distilled liquor made from fermented potatoes or cereal grains and is typically 80 proof.
Whiskey is a distilled drink that is typically 60-110 proof.
Wine Coolers are wine is often diluted wine, sometimes carbonation may be added, through a secondary fermentation process. Typically; 10-30 proof.
Wine is made from fermented grapes, typically 18-32 proof.
NOTE: Some alcohol may not be found in all areas.