What Happens When You Drink
When you take a drink, about 20 percent of the alcohol is absorbed in your stomach; the remaining 80 percent is absorbed in your small intestine. How quickly the alcohol is absorbed depends upon the concentration of the alcohol in the drink (vodka, for example, will be absorbed faster than beer, because vodka has a higher alcohol concentration) and whether you've just eaten a big meal. A full stomach will slow down alcohol absorption.
After the alcohol is absorbed, it enters your bloodstream and is carried throughout your body. As the alcohol acts upon the body, the body is simultaneously working to remove it. The kidneys and lungs remove about 10 percent of the alcohol in the urine and the breath (which is why a breathalyzer test can be used to measure a person's blood alcohol level). The liver breaks down the rest of the alcohol into acetic acid.
After just a few drinks, the physical effects of alcohol become apparent. These effects are related to the blood alcohol concentration (BAC). The BAC goes up when the body is taking in alcohol faster than it can release it. To learn about specific impairments at various BAC levels, see How Alcohol Works: The Effects of Alcohol.