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How Long Does Alcohol Stay in the Body?

The longstanding understanding is that your body will metabolize one alcoholic drink per hour. This rule leads to the recommendation that in any given sixty-minute period, a person should not have more than one “unit” of an alcoholic beverage, which is the equivalent of one bottle of beer, one five-ounce glass of one, or one-and-a-half ounces of distilled spirits. This rule is a general guideline, however, and it is not an accurate predictor of how long alcohol will stay in your body. That length of time and the factors that affect it are complicated and will vary dramatically from person to person.

The primary factors are how much and how often a person drinks, the type of alcohol he drinks, his age, genetic background, family history, and general physical health. Alcohol is a foreign substance that is toxic to a person’s body at high doses. Your body works to metabolize toxins, and a healthier person or someone who has a genetic predisposition for a faster metabolism of alcohol will rid himself of this toxicity faster than an unhealthy or aged person.

Each unit of an alcoholic beverage contains approximately 0.6 fluid ounces of pure alcohol. A person’s bloodstream absorbs alcohol very quickly, often in less than ten minutes after that person begins to consume a drink, with peak absorption occurring at roughly 40 to 60 minutes after the drink is consumed. A person will therefore begin to feel the effects of an alcoholic beverage quickly, but will not experience the full effects of the alcohol in a single drink for up to an hour afterwards. A person who is eating while consuming alcohol will experience slower alcohol absorption as his body works to metabolize both the food and the alcohol simultaneously.

Some amount of that 0.6 fluid ounces of pure alcohol will remain in the bloodstream of most people for up to two hours after a single unit of an alcoholic drink is finished. Because the full effects of a single drink are not experienced for up to an hour after it is consumed, a person who drinks very quickly will be at a greater risk for alcohol poisoning, in which the concentration of alcohol in his body overwhelms his body’s ability to metabolize and flush the alcohol out. When that happens, a person might begin to act incoherently, lose consciousness, vomit, or lose control of basic metabolic functions.

The amount of alcohol in a person’s body is typically represented by a measure of his blood alcohol concentration, or “BAC”. An average person’s body will metabolize alcohol at a rate of .015 of BAC per hour. A person with a BAC level of .08, for example, will continue to have some trace of alcohol in his system for more than five hours after he reaches that level (i.e. .08 divided by .015 equals 5.33). Again, this formula represents an average across a large population of drinkers, and it is not an exact measure of how long alcohol will stay in the bloodstream of any specific individual.

These guidelines and averages are most useful in helping a person to manage or monitor the amount of alcohol in his system. For example, a person might estimate that his BAC will be at a maximum of .045 after he consumes three units of alcoholic drinks in two hours. At that point, he will know that there will be traces of alcohol in his system for three more hours.   


Harmony Place offers a full continuum of luxury residential care, from detox to transitional living. If you or someone you love is struggling with alcohol, there is help. Contact us today for a private consultation and information on how we can help you create a custom plan of treatment for long-term success.