How Long Alcohol Stays In Your System
People may say they can sober up quickly, but their physiology tells a different story. Alcohol is one of the most predictable chemical reactions in the human body, and virtually everyone breaks alcohol down at almost precisely the same rate.
Alcohol metabolism: breaking it down
Alcohol is metabolized (broken down) by the body at a rate of 0.016% per hour.1 It doesn’t matter if you are 6’4” or 4’6” or if you drank red wine or moonshine. Once your blood alcohol concentration (BAC) reaches a certain level—no matter how it got to that level—your body needs time to break the alcohol down and remove it from your system.
Blame your enzymes
The main way that alcohol is broken down in the body is through an enzyme called alcohol dehydrogenase. Alcohol dehydrogenase takes a molecule of ethanol (the alcohol you drink) and breaks it apart. The funny thing about this enzyme is that you cannot make it work any faster, no matter how much alcohol you give it to break down.2
Alcohol dehydrogenase is like a one-lane tunnel; no matter how many cars (alcohol molecules) are waiting to get through the tunnel (enzyme), only one can go through at a time. The more you drink, the more molecules are waiting to “get through” the enzyme.
How long does it take to metabolize alcohol?
On the bright side, this precise metabolism makes it fairly easy to determine how long it will take for you BAC to reach zero. Take a BAC of 0.16, for example, a BAC that is twice the legal limit (BAC 0.08) in some countries. Since your body (and every body) metabolizes alcohol at 0.016% per hour, it will take 10 hours for a person with a BAC or 0.016 to reach a BAC of 0.00.
In fact, you can determine BAC for each hour that you spend metabolizing alcohol. Let’s continue using the same example. Assume a person has a BAC of 0.16 at two in the morning. She stopped drinking and is simply sobering up (letting her enzymes break down alcohol). Even without measuring each hour, you already know her BAC for the next 10 hours.
Therefore, if the person with a BAC of 0.16 leaves the pub at two in the morning, her BAC will reach zero at noon the next day. At any time before seven in the morning, she will be above the legal limit.
When will I reach 0.00 BAC?
You can calculate the time it takes to reach 0.00 BAC from any starting BAC. The table below includes metabolism times for a few BAC levels. If you don’t know your starting BAC, you can use a BAC calculator to estimate your BAC based on the number of drinks you’ve had and some other factors.
|BAC Level||Hours Until 0.00 BAC|
|0.03||~2 (1.875 h)|
What can I do lower my BAC my quickly?
Sadly, there is no practical way to lower your BAC any faster than your enzymes will work. Once your BAC reaches a certain level, all you can do is wait for your liver to do its job.
But I heard there is a way to sober up by…
People have tried countless ways to speed up the sobering process. None of them actually works. You can try to drink coffee, which may make you feel more awake and alert, but this doesn’t change the rate at which your enzymes are breaking down alcohol. You can eat fatty foods, drink water, exercise—none of these will change the rate of your alcohol dehydrogenase.
Are there impractical ways to speed up alcohol metabolism?
The 0.016% BAC is an excellent rule of thumb for almost everyone, but there are some exceptions. In people who drink very heavily (problem drinking), the rate of alcohol metabolism is slightly faster. Heavy drinking induces the formation of another enzyme, CYP2E1.3 While the enzyme alcohol dehydrogenase is still plodding along, the newly produced CYP2E1 helps metabolize alcohol. The cars are still moving through the tunnel, but now a new tunnel has opened up called CYP2E1. Thus, years of heavy drinking can speed up the metabolism of alcohol slightly.
This impractical method can be taken too far, however. Years and years of heavy drinking can actually damage the liver (cirrhosis). When the liver becomes cirrhotic, it negatively affects liver enzymes like alcohol dehydrogenase and CYP2E1. So, people with advanced liver disease actually have slower rates of alcohol metabolism.3
Okay, there is one practical way to speed up alcohol metabolism
People who eat before they drink metabolize alcohol slightly faster than people who drink on an empty stomach.4 In other words, the rate of alcohol metabolism is faster on a full stomach than an empty stomach. Scientists believe this may be due to increased blood flow to the liverand increased activity of liver enzymes. Having food in the stomach (intestines, really) induces more enzyme activity in the liver than in the fasting state. Using the previous analogy, the tunnel gets wider and allows more cars to go pass (The activity of alcohol dehydrogenase is increased temporarily).4
However, eating a meal is really not something you can do after your BAC is at a certain level. Moreover, the speed of alcohol metabolism only increases a small amount on a full stomach. This means you still need to wait a specific amount of time for your liver enzymes to break down the alcohol in your system.
Alcohol absorptionis not as constant as alcohol metabolism
While alcohol metabolism is extremely constant (0.016% per hour), alcohol absorption can vary substantially. The rate of alcohol absorption influences how rapidly your BAC will rise (not how fast your BAC will fall, because that reflects alcohol metabolism).
Alcohol absorption is affected by your size, gender, how much you drink, and how fast you drink.3,5 The more alcohol you drink, the more rapidly the body absorbs it. Likewise, BAC rises faster if you drink a certain amount of alcohol all at once rather than over a long period of time.
Alcohol absorption is NOT affected by the type of alcoholic beverage3. Alcohol absorption is determined by the amount of alcohol in the beverage, not by how that beverage is prepared.In other words, a shot of whisky would be absorbed at virtually the same rate whether it was placed in a whisky sour or downed neat.
Food and alcohol absorption
The effect of food and alcohol absorption is complicated. If you drink on a full stomach, the rate at which the alcohol and food moves from the stomach to the intestines slows down. Since alcohol is mainly absorbed from the intestines, this slows down absorption. This means BAC levels rise more slowly. This is especially true if the meal is especially fatty.
On the other hand, eating a meal increases blood flow to the stomach, intestines, and liver. This increased blood flow actually speeds up absorption. But, as mentioned previously, this blood flow also increases enzyme activity in the liver, which speeds up alcohol metabolism slightly.
The bottom line: Food affects the absorption and metabolism in a variety of ways, but they mostly cancel each other out.
BAC and feeling drunk
Alcohol intoxication (or feeling drunk) roughly correlates with BAC.6 Obviously, the higher your BAC, the more drunk you will feel. In people who do not abuse alcohol, the effects of alcohol are predictable (shown in the table). In heavy or problem drinkers, these effects may not occur until the BAC is much higher.7
|BAC between 0.01 and 0.10||Mild euphoria, mild problems with coordination and attention|
|BAC between 0.10 and 0.20||Impaired judgment, slurred speech, and trouble walking|
|BAC between 0.20 and 0.30||Lack of coordination,confusion, nausea and vomiting|
|BAC above 0.30||Stupor, loss of consciousness, coma death|
- The rate of alcohol metabolism is remarkably constant.
- BAC will decrease by 0.016% per hour a person stops drinking
- There is no practical way to increase the rate of alcohol metabolism
- Alcohol metabolism is slightly faster in someone who had a meal before they started drinking, but this increase is very small
- Heavy drinkers metabolize alcohol faster than light drinkers or non-drinkers. However, the rate of alcohol metabolism drops substantially in advance liver disease.
- While the rate of alcohol metabolism is constant, the rate of alcohol absorption can vary.
- In people who do not abuse alcohol, BAC is a good gauge of how "drunk" they will feel. On the other hand, people who abuse alcohol generally require much higher BAC levels to achieve the same drunk feeling.
Estimate Your BAC Level
To help estimate your BAC (Blood Alcohol Concentration) level, we have created a very simple BAC calculator tool based on a basic version of the Widmark Formula. To use this tool you will need to provide a few pieces of information such as your gender, weight, number of standard drinks and finally how long since you started drinking. Once you have entered this information, the tool will estimate your BAC level and give you a rough idea of how long the resulting BAC level would take to pass through your system. Please note, this tool provides an estimate and you should not drive a vehicle if you have any alcohol in your system.
Try The BAC Calculator Tool
- Wilkinson PK, Sedman AJ, Sakmar E, Kay DR, Wagner JG. Pharmacokinetics of ethanol after oral administration in the fasting state. Journal of pharmacokinetics and biopharmaceutics. 1977;5(3):207-224.
- Matsumoto H, Fukui Y. Pharmacokinetics of ethanol: a review of the methodology. Addict Biol. Jan 2002;7(1):5-14. doi:10.1080/135562101200100553
- Cederbaum AI. Alcohol Metabolism. Clinics in liver disease. 2012;16(4):667-685. doi:10.1016/j.cld.2012.08.002
- Ramchandani VA, Kwo PY, Li TK. Effect of food and food composition on alcohol elimination rates in healthy men and women. J Clin Pharmacol. Dec 2001;41(12):1345-1350.
- Baraona E, Abittan CS, Dohmen K, et al. Gender differences in pharmacokinetics of alcohol. Alcohol Clin Exp Res. Apr 2001;25(4):502-507.
- Marx J, Walls R, Hockberger R. Rosen's Emergency Medicine-Concepts and Clinical Practice. Elsevier Health Sciences; 2013.
- Sullivan JB, Jr., Hauptman M, Bronstein AC. Lack of observable intoxication in humans with high plasma alcohol concentrations. J Forensic Sci. Nov 1987;32(6):1660-1665.