There are several biological factors that can increase or decrease the degree of intoxication when an individual drinks alcohol. The effect of these biological factors, for the same number of drinks, are summarized below. Click on the appropriate links to find additional discussion in other modules.

Figure 2.8 A variety of factors influence the degree of alcohol intoxication.

Body mass: larger people have a lower BAC

Gender: females have a higher BAC

Age: young people (< age 24) are less sensitive to early intoxicating effects of alcohol such as sedation and motor coordination, but they are more sensitive to the memory loss produced by alcohol

Tolerance: a person who drinks regularly is less sensitive to alcohol and has a lower BAC. Interestingly, tolerance does not develop to the lethal dose of alcohol.

Metabolism: a person with a faster metabolism rate has a lower BAC

Race/ethnicity: certain populations can metabolize alcohol more quickly leading to a lower BAC, or metabolize alcohol more slowly leading to a higher BAC.

Genetics: different forms of the same gene can lead to different degrees of alcohol metabolism; this occurs in the general population, as well as in specific racial/ethnic populations.