When drinking alcoholic beverages you use your natural resistance to determine whether or not you feel the effects of the beverage (it is a poison after all), generally though size plays a big factor on how well someone can hold their drinks, use the formula below to take a resistance test against alcohol after every drink:
The drink factor is a combination of both how much you have had to drink and how strong the beverages are. When drinking alcoholic beverages keep a tally of your current ‘drink factor’ by multiplying the number of drinks by each drinks associated strength. See the table below for the relative strengths of various alcoholic beverages.

Alcoholic Beverages

If you fail your alcohol resistance test you are drunk, although the degree to which you are affected depends on how many times you fail your test. Also should you get into a bar fight (see Bar Fighting rules) or be engaged in actual combat your degree of drunkenness will affect you combat skills and prowess. For every time you fail an alcohol resistance test you move up one degree of drunkenness. All effects of drunkenness are cumulative and last for the duration of drunkenness. After one hour (in-game time) you naturally fall back one degree of drunkenness. If you pass out you generally stay that way for at least a half-rest. After a half-rest roll you go down 1d4+2 degrees while after a full-rest you go down 1d4+4 degrees. If after a half or full rest you did not drop down enough degrees to no longer be drunk you are instead hung over. Once you are hung over you remain so until having a full rest, after which time all effects are gone.

Degrees of Drunkenness

As an example let’s assume a human with stamina of 15 and natural resistance of 35 has a single beer (worth 1 drink factor point). His alcohol resistance is then 35 + 15 – 1 = 49. He rolls a 23 on a d100 and is therefore not drunk. Next he drinks some dwarven spirits (worth 4 drink factor points because dwarven spirits are 1 point stronger than regular spirits). 35 + 15 – (1+4) = 45. This time he rolls a 46 and is therefore drunk in the 1st degree. Next he drinks some wine (worth 2 drink factor points). 35 + 15 – (1+4+2) = 43. This time he rolls a 68 and is therefore now drunk to the 2nd degree.

Racial Modifiers

Some races react differently to alcohol than others
Elf, Half-elf
Skip Degree 2 Drunkenness entirely
Dwarf, Gnome
Immune to Alcohol Poisoning & Hangovers
At Degree 3 Drunkenness +2 Charm instead of -4 Charm
Orc, Half-Orc
Immune to alcohol induced vomiting
At Degree 4 Drunkenness can no longer use Flight ability
Can roll a Stamina test to resist passing out that round
Immune to passing out at Degree 7