When ingested, alcohol passes from the stomach into the small intestine, where it is rapidly absorbed into the blood and distributed throughout the body. Because it is distributed so quickly and thoroughly the alcohol can affect the central nervous system even in small concentrations. In low concentrations, alcohol reduces inhibitions. As blood alcohol concentration increases, a person’s response to stimuli decreases markedly, speech becomes slurred, and he or she becomes unsteady and has trouble walking.

The liver is responsible for the elimination – through metabolism – of 95% of ingested alcohol from the body. The remainder of the alcohol is eliminated through excretion of alcohol in breath, urine, sweat, feces, milk and saliva. The body uses several different metabolic pathways in its oxidation of alcohol to acetaldehyde to acetic acid to carbon dioxide and water.

Healthy people metabolize alcohol at a fairly consistent rate. As a rule of thumb, a person will eliminate one average drink or .5 oz (15 ml) of alcohol per hour. Several factors influence this rate. The rate of elimination tends to be higher when the blood alcohol concentration in the body is very high or very low. Also chronic alcoholics may (depending on liver health) metabolize alcohol at a significantly higher rate than average. Finally, the body’s ability to metabolize alcohol quickly tend to diminish with age.