Drinking an intricate part of life in any IRE game. So why does it have to be so unrealistic. Sure, the person gets drunk, and have some dizziness effects and slurred speech, but it needs more.

For a day after soberness, they gain a hangover where they are prone to sleepiness, require them to drink often, and have a mini-sun sensitivity.

To reduce the effects, during drunkeness, the person should eat more, not drink alchohol or water (since for those who lives in urban myths, water does concentrate alchohol in blood stream - if you want an explanation bug me), and eat fruit.

Just some ideas.