An average person's Alcohol Threshold (AT) is equal to his Constitution score, but this number can be modified by several other factors. Any racial, magical, or class-based bonuses to resist poison add to this number, the Endurance feat adds +4 to this number, and the Hard Drinking feat doubles a character's AT (Constitution score and all other modifiers are doubled).
For each size category smaller than Medium that you are, your AT is reduced by half. For each size category larger, double your AT. For example, the AT of the average Halfling is only 5, whereas a great wyrm red dragon would have an AT of 496. Once you reach your AT, you become tipsy. As you drink more, you progress through the various levels of intoxication, with a number of Alcohol Units (AU) equal to your threshold increasing your drunkenness to the next category.
For example, Stumpy has a Constitution of 14. He drinks two shots of whiskey (12 AU each, total 24 AU). This exceeds his AT, so he becomes tipsy. Another 4 AU will take him to 28, putting him in the merry category.
The DM may give a temporary bonus to a character's alcohol threshold of up to +2 from various factors, such as a full stomach or magical enhancements.
Drink Sizes
Servings of alcohol are measured in shots. A shot does not denote any real-world significance; rather, it is simply a convenient word to measure small volumes of liquid in game terms. The number of shots contained in various drinking vessels is as follows.
Drink Strengths
The strength of the drink is measured on a scale, with 0 being no alcohol content, and 10 or higher being powerful beverages. The following table should not be regarded as a definitive list of drinks, but rather a rough guide to how to use alcohol strengths. A drink's total effect is measured in AU. The AU of a given drink is the product of its number of shots times its strength. For example, a mug (4 shots) of wine (Strength 4) is a total of 16 AU.
Categories of Drunkenness
Alcohol is basically, a poison. The more you drink, the greater the effect it has. There are several levels of intoxication, each accompanied by penalties to certain abilities, and a slight bonus to resist pain.
Tipsy: Judgment slightly impaired, but no noticeable effects. -1 penalty to attack rolls, skill checks, ability checks, and Reflex saves. No effect on movement or hit points. Must make a Concentration check (DC 10 + spell level) to cast spells or take similar actions.
Merry: Inhibitions lower, voices raise, and balance wavers slightly. -2 penalty to attack rolls, skill checks, ability checks, and Reflex saves. +1 temporary hit point per Hit Die. No effect on movement. Must make a Concentration check (DC 10 + spell level) to cast spells or take similar actions.
Drunk: Dizzy and disoriented, words slurred. -4 penalty to attack rolls, skill checks, ability checks, and Reflex saves. +2 temporary hit points per Hit Die. Can safely take one action each round, but nust make a Balance check (DC 10) to both move and take an action. Falls down on failure. Must make a Concentration check (DC 10 + spell level) to cast spells or take similar actions.
Hammered: Can't walk in a straight line, generally incoherent. -8 penalty to attack rolls, skill checks, ability checks, and Reflex saves. +3 temporary hit points per Hit Die. Can safely take one action each round, but nust make a Balance check (DC 10) to both move and take an action. Falls down on failure. Must make a Concentration check (DC 10 + spell level) to cast spells or take similar actions.
Plastered: Communication is nearly impossible, as is standing up. -16 penalty to attack rolls, skill checks, ability checks, and Reflex saves (though the character can take no actions, so it usually doesn't matter). +4 temporary hit points per Hit Die (but usually unable to take advantage of this). Must make a Concentration check (DC 10 + spell level) to cast spells or take similar actions. Character is nauseated, and the only action he can normally take is a single move action per round. A character who is plastered can, however, choose to take one standard action other than a move, but is then stunned for the next 1d6 rounds.
Unconscious: Character is unconscious, usually from sickness or extreme dizziness and confusion.
Recovery and Hangovers
A character recovers at a rate of 8 AU per hour. Additionally, eight hours of uninterrupted sleep enables him to recover completely. A character who has become drunk or worse suffers a hangover once he sobers up. A hangover consists of headaches, nausea and other unpleasant side effects. After recovering from drunkenness, a hangover begins. While hung over, a character suffers the same penalty to his attack rolls, skill checks, ability checks, and Reflex saves of the highest drunkenness category he reached the night before. Every two hours, the severity reduces by one category until the penalties go away.
A Craft (alchemy) check (DC 20) will allow a character to brew a hangover or drunkenness remedy. Characters with 5 or more ranks in Heal get a +2 synergy bonus to this check. Most such folk remedies sell for 2 gold pieces per dose, and many inns and taverns make as much money sobering up their patrons as getting them drunk. A character can only benefit from one dose of a folk drunkenness remedy per day. Remedies have an effect either on current drunkenness, or on hangovers. Particular effects may vary, the following is one example.
Hair of the Dog: This foul-tasting concoction doesn't even try to hide its ingredients: A clump of dog hairs float atop a green-brown broth filled with mashed leaves. The necessary ingredients for 5 doses can be found in a typical forest with an hour of searching and a successful Survival check (DC 12). Two hours of work and a Craft (alchemy) check (DC 20) can turn the ingredients into 5 doses, each the size of a small cup. A dose of hair of the dog reduces the character's penalties from a hangover as if 2 hours had passed. Only one such drink can have an effect per day.