How Long Does Alcohol Stay in the Body?

David J. Hanson, Ph.D.

After alcohol is absorbed into the bloodstream it leaves the body in two ways. A total of about ten percent leaves through the breath, perspiration, and urine. The remainder is broken down through the process known as metabolism.

The rate at which alcohol is metabolized is the same for virtually everyone regardless of their height, weight, sex, race or other such characteristics.

Alcohol is metabolized at the rate of .015 of blood alcohol concentration (BAC) every hour. 1 Thus a person with a very high BAC of .15 will have no measurable alcohol in the bloodstream after ten hours (.15 divided by .015 = 10). Here are some other examples:

BAC Level Metabolism Time in Hours
.10 6.66
.08 5.33
.05 3.33
.02 1.33

It’s important to remember that BAC can continue to rise for a period of time after the last drink is consumed. For useful information about the biphasic curve and our reactions to alcohol How Alcohol Affects Us: the Biphasic Curve.

We can easily control the rate at which our BAC rises and how high it goes. Here are some hints:

Estimate Your BAC

Estimate the Blood Alcohol Concentration (BAC) you would reach when drinking over a variety of time periods.

From: How to Control Your Drinking by William R. Miller and Richard F. Munoz.

Although we can control how high our BAC goes, we can’t speed up our metabolism of alcohol. Drinking coffee, exercising or taking showers and similar behaviors have no effect on alcohol metabolism. Only time can do that.

To avoid hangovers keep BAC low, no higher than about .05 to .06. 4 There is no scientific or clinical evidence that any of the hangover “remedies” on the market are of any value whatsoever. There is some evidence that, other things being equal, clear distilled spirits such as gin and vodka are less likely to cause hangovers. 5 But it’s always best to avoid drinking too much alcohol.

The human body produces alcohol throughout life 24/7. It’s called endogenous ethanol production and the volume of alcohol produced depends to some degree on what foods have been eaten. On average, it appears that people can produce about one ounce of absolute or pure alcohol each day. 6 However, the law doesn’t distinguish between alcohol produced in the body and that which is consumed.

Unfortunately, so-called alcohol breath testing machines only estimate BAC, which can only be measured by testing the blood itself. Breath, perspiration and urine can only be tested to estimate the amount of alcohol in the bloodstream. 7

Research indicates that a large proportion of people tested with a Breathalyzer or similar breath machine will receive a reading higher than their actual BAC. This means that many innocent drivers are falsely convicted of DWI/DUI. 8

But there is good news. You can easily avoid both alcohol-impaired driving and unfair DWI/DUI convictions by abstaining, drinking in moderation, or either being or using a designated driver (DD) who consumes no alcohol.

This web site does not provide medical or legal opinion or advice of any type and none should be inferred. For health or legal questions always consult a competent professional.

References and Readings

filed under: Drinking and Driving

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