How Long Does it Take for Alcohol to Clear Your System?

by Katrina Cain

A row of spirits at the Hard Rock Cafe in Prague taken by Clock.

My interest in answering this question was sparked after enduring one of the world’s worst hangovers. The next day, I found myself wondering whether it was safe to drive; forgetting the actual physical feeling of ick, and considering the lingering effects on my ability to safely drive. So you want to sober up? Here are some things you need to know.

The most common answer seems to be one drink will metabolize in one hour; therefore, you will be under the legal limit one hour after consuming one standard size drink. A standard size drink is 12 ounces of beer, or 5 ounces of wine, or 1.5 ounces of liquor (gin, rum, vodka, etc.). A pint of beer at a local brew pub is 16 ounces. One mixed drink, for example, a rum and coke should contain about 1.5 ounces of rum (unless you have tipped your bartender and server big, in which case, they will sometimes overpour).

Alcohol clearance rates are affected by other factors; how much consumption over a given period of time, presence or absence of food, medication interaction, body weight and physical health, your gender and age; the list goes on and on. For these reasons, it is almost impossible to set a universal standard. There are a couple of medical definitions to understand about the way alcohol is dealt with in your body: absorption and elimination or metabolism.

Absorption is the deposit of alcohol into your blood, tissues and organs. Once the drink enters the stomach and small intestine, the alcohol diffuses through the membranes of these organs into the blood stream. If you’ve just eaten a high fat and/or protein meal, absorption will be slower – simply put, there is more material that the alcohol has to move through before being diffused into the blood stream. This is why many pubs insist on serving food with their drinks; fatty foods like french fries, onion rings, ribs, wings and nachos. Of course, the salty nature of these snacks encourages thirst, begetting another round of drinks. The speed of absorption also depends upon how fast you are drinking. If you slam down 4 pints in 10 minutes, the maximum effect might not be felt until 2 hours after consumption is complete; even if you stop drinking.

Elimination or metabolism is the breakdown of the alcohol in your body; mainly done by the liver. A very small amount leaves your body, unchanged in your breath and urine. The former allows the police to test your BAC with a breathalyser test. The main bulk, however is digested by your liver in much the same way as food; with lots of involved steps; the final product being water and carbon dioxide. So, in the case of those 4 pints drunk in 10 minutes, reaching maximum BAC at 2 hours after your last drink and using the one drink per hour model you have 4 x 16 ounces = 64 ounces. One standard drink is 12 ounces, so 64/12 = 5.3 drinks. Assuming the elimination of one drink/hour, starting at 2 hours after the last drink, you are looking at 7 to 8 hours before you are sober. I just want to reiterate, that there are lots of other factors influencing this estimate, but what we can take away from this is that if you stop drinking at 2 am when the bar shuts down and have to leave for work at 7 the next day; you may still have a BAC higher than the legal limit.

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