Alcohol is treated as a specialized poison. Ales and wines usually have a fortitude save DC of 10-15, most human spirits a 15-20 dwarven or special spirits would have a 21+. Like most poisons, continued “doses” increase the DC of checks that must be made to stave off drunkenness.
Fortitude saves at a -2 Morale penalty to avoid going to Stage II. The temporary Constitution bonus to fort saves does not apply to drinking fort saves.
Upon entering Stage II, the character must immediately make a second Fort save at the DC of the beverage that caused them to enter this stage. Failure indicates taking 1d8 subdual damage. While in Stage II, the character takes a -2 temporary morale penalty to all mental stats, but keeps the benefits from Stage I. The Stage II penalties have a separate 1d4 hour window from the Stage I bonuses.
After a failed fort save while continuing to drink while in Stage II, the following occurs –
Character loses all benefits from Stage I
Character takes an additional -2 penalty on ALL stats for 1d4 hours. These negatives are innate, and stack with the penalties from Stage II.
Character must make a secondary Fortitude save at the adjusted DC of the imbibed liquid, or lose consciousness or “black out” for 2d4 hours.
If a character reaches Stage II or III of inebriation, they must make a Fortitude save at a DC of what they were drinking (if mixing drinks, they take the highest DC and add 2 for each additional alcohol source) or become hungover when the benefits/penalties of their inebriation state wear off.
Hungover characters are treated as Fatigued, but undertaking any activity which requires a check which is affected by statistics (attacks, skills, some spells) cause them to become exhausted. The duration of a hangover is 1d4 hours for each hour spent Inebriated.
DM may rule that repeated exposure to high levels of drunkenness, or extended periods of hung-over exhaustion may have longer-term detrimental effects on a character (subdual damage or stat penalties which require abstinence and rest to go away).
Any time a drinker fails a fortitude save which would progress them to inebriation, they can opt to vomit, in lieu of progressing. This reduces a drinker one stage of inebriation, but penalties to fort saves for continued exposures continue to last until the character has had a full rest, instead of the normal 1d4 hours. If a character vomits more than once in a drinking bout, they immediately become Fatigued, and they will have a hangover which lasts a minimum 8 hours, even if they are only at Stage I. Monks and Druids are still affected by alcohol, regardless of class abilities, but Dwarves +2 racial bonus against poison also carries over to alcohol. Most creatures with an immunity to poison will have a bolstered resistance to inebriation, like dwarves.