It is estimated that over 85% of adults in the United States have consumed alcohol at some point during their lifetime. Of these individuals, over 70% have had a drink within the past year, and upwards of 55% of individuals have had a drink within the past month. Alcoholic beverages contain the psychoactive substance “ethanol,” which is known to temporarily improve mood, increase self-confidence, decrease anxiety, and promote socialization.
Alcohol intoxication is often viewed as pleasurable due to the fact that it increases the neurotransmission of GABA (gamma-aminobutyric acid) and enhances neuroelectrical production of alpha waves. As a result of these intoxicating effects, it’s no wonder that over 16 million adults in the United States have “alcohol use disorders” and are unable to control their drinking. Though alcohol is marketed as a relatively benign beverage and isn’t often perceived as a “drug,” if compared to other popular substances, it would be considered among the most addictive drugs in the world.
Despite short-term beneficial effects of alcohol, its consumption is often associated with unwanted effects such as: impaired fine motor skills and coordination, poor judgment, decreased attention span, slower reflexes, and blurred vision. As a result of these unwanted effects, alcohol consumption can make it dangerous to operate a motor vehicle or heavy machinery after consumption. To keep yourself safe and avoid endangering the lives of others, it is important to understand how long alcohol stays in your system
How long does alcohol stay in your system?
For the overwhelming majority of individuals, alcohol is metabolized at a relatively predictable rate. Most people can expect blood alcohol concentrations (BAC) to drop at a rate of .015 per hour. This means that following your last alcoholic drink of the night, the alcohol in your body is being metabolized and eliminated at a rate of .015. If you managed to get your BAC to 0.10, it would take just under 7 hours for the alcohol to get eliminated from your system.
Starting BAC of 0.10
Below is an example of how long it would take your blood alcohol concentration (BAC) to reach 0.00 based on the medically-accepted elimination rate of .015 per hour.
- After 1 Hour: 0.085
- After 2 Hours: 0.07
- After 3 Hours: 0.055
- After 4 Hours: 0.04
- After 5 Hours: 0.025
- After 6 Hours: 0.01
- After 7 Hours: 0.00
Though some people may speculate or hypothesize their BAC after drinking, these speculations are usually inaccurate. As a result of these inaccurate subjectively hypothesized BACs, many people make the mistake of operating motor vehicles long before their BACs have dropped sufficiently to facilitate a safe driving experience. Therefore, it is important to purchase an accurate BAC tester to objectively verify whether your BAC is low enough to drive prior to hitting the road.
To put things in perspective, an average 180 lb man would need to consume approximately 5 drinks per hour to reach a BAC of 0.10. However, a 140 lb woman would only need to consume approximately 3 drinks per hour to reach a BAC of 0.10. The legal limit for driving under the influence is a BAC of 0.08, meaning if you were at a BAC of 0.10, it would take up to 2 hours before your BAC would drop within legal range (below 0.08) to operate a motor vehicle.
Should someone have been “binge drinking” or consuming large quantities of alcohol in a short duration, alcohol could remain in their system for much longer than expected. Consider a 180 lb man who binges and consumes 10 beers (12 oz) within one hour. He would likely reach a BAC of approximately 0.21, taking an estimated 9 hours before he would be beneath the legal driving limit of 0.08, and an estimated 14 hours for complete elimination.
Factors that influence blood alcohol content and absorption
Although the drop in blood-alcohol concentration (BAC) is predictable at a relatively constant rate of 0.015 – the extent to which your BAC increases is subject to significant individual variation. In other words, it will take a greater number of 12 oz beers per hour to reach 0.08 for a 240 lb male (5 beers), compared to a 120 lb woman (2 beers). Other factors that influence blood alcohol levels include: age, body mass, body fat, metabolism, type of alcohol, food intake, pharmaceutical medications, etc.
The total amount of alcohol you consume will influence the duration over which it stays in your system. A relatively simple rule of thumb holds true: the more alcohol you consume, the longer it takes for alcohol to clear from your system. Though individual factors play a role in determining peak blood alcohol concentration, the more you drink, the longer you should expect it to take for alcohol to clear from your body.
Let’s say you’re reflecting on a couple of different nights in which you drank over the past couple months. One night you drank 5 beers per hour, and the other night you binged and drank 10 beers per hour. The night you drank 5 beers per hour would’ve resulted in quicker clearance of alcohol from your system due to the fact that the dosage was half that of the night you drank 10 beers per hour.
Rate of Consumption
Someone who drinks 10 beers per 30 minutes will have an increased “rate of consumption” compared to an individual who consumes 10 beers per 5 hours. The rate by which you consume alcohol will determine your peak BAC. In general, the greater the amount of alcohol that you consume within a shorter duration, the greater your peak blood-alcohol concentration.
Though it may take awhile to fully clear alcohol from your system, most people are concerned with clearing enough to stay below the driving limit of 0.08. A person drinking 10 beers over the course of 5 hours may be able to stay below the limit (depending on their body weight), whereas that same person drinking 10 beers in 30 minutes would have no realistic shot at driving sober.
Potency of Alcohol + Carbonation
The greater the percentage of alcohol within a drink by volume, the easier it is to reach a high blood-alcohol concentration. Someone drinking a pilsner beer may consume between 3% and 6% alcohol by volume (ABV), whereas a person drinking vodka may consume over 40% alcohol by volume. In other words, it would take much less of the vodka (at 40% alcohol by volume) to reach a blood-alcohol concentration of 0.08 compared to an individual consuming the pilsner beers.
Assuming that an individual drank 12 oz of a 40% ABV beverage, they would get drunk at an 8-fold quicker rate than if they drank 12 oz of a 5% ABV beverage. Whenever factoring in clearance, it is important to consider the potency of the alcohol you consumed. A higher potency will take longer to clear from your system because the beverage contained a greater amount of total alcohol.
It is also important to consider whether the beverage you consumed was carbonated. Carbonated beverages generally are absorbed at a quicker rate than non-carbonated beverages, and thus can get you drunk more quickly. This is due to the fact that carbonation forces alcohol from the stomach lining into the bloodstream.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/17720590
There are a variety of individual factors that can influence alcohol absorption, metabolism, and how efficiently your system processes it. Understand that certain factors may have a greater influence (e.g. body mass) compared to others (e.g. sex). That said, all of these factors should be considered if you want to understand variability among people in their ability to handle alcohol.
- Age: The younger an individual, the more efficiently they are able to metabolize alcohol. Older individuals have greater difficulty metabolizing alcohol due to the fact that endogenous levels of enzymes have diminished. Specifically, metabolizing enzymes that diminish with age include: alcohol dehydrogenase , acetaldehyde dehydrogenase, and cytochrome P-4502E1. In addition, the liver of older individuals isn’t considered as robust as that of younger individuals, leading to decreased ability to metabolize alcohol, and higher blood-alcohol concentrations.
- Body fat / muscle: Individuals with a higher percentage of body fat in proportion to body mass (height and weight) often have a more difficult time absorbing alcohol. This is due to the fact that body fat tends to contain minimal water, forcing alcohol to stay in the bloodstream until it can be processed by the liver. On the other hand, those with a lower percentage of body fat in proportion to body mass – and especially those with a lot of muscle – absorb alcohol more efficiently. As a result, individuals with low fat and high muscle often are able to maintain lower BAC levels than the high fat and low muscle.
- Body mass: It is no secret that tall, heavyset individuals with high bodyweight can handle more alcohol than short individuals with lower bodyweights. Since men are often taller and weigh more than women, it usually takes more “drinks” to get them drunk. It would take a 6’6″ 300 lb man longer to reach a BAC of 0.08 than a 4’5″ woman weighing 120 lbs. Assuming each of these individuals consumed 3 drinks, the man would clear alcohol sooner from his system because he drank less in proportion to his body mass, whereas the woman consumed more in proportion to her body mass.
- Drugs / supplements: It is important to consider that various over-the-counter medications (e.g. aspirin), pharmaceutical prescriptions, and even supplements can influence alcohol metabolism and drug serum concentrations. Some medications are thought to interact with alcohol and perpetuate its intoxicating effect. It could be speculated that certain drugs (or supplements) may alter the absorption of alcohol, resulting in BAC increases (or decreases) based on the specific substance.
- Food intake: Individuals that consume alcohol after eating a meal and/or along with food will have lower blood-alcohol concentrations than individuals who consume alcohol on an empty stomach. Food consumption prior to drinking prevents a BAC spike by keeping alcohol in your stomach lining for a longer duration before it is absorbed within the bloodstream. Consuming a large meal prior to drinking can help mitigate BAC spikes.
- Genetics: There is significant genetic influence over your ability to metabolize alcohol. It is known that variants of genes responsible for producing the enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) can influence alcohol metabolism. Should you have a specific genetic abnormality that influences ADH or ALDH, you could end up with inefficient processing of alcohol and end up with a longer window of detoxification.
- Metabolism: People with quicker baseline metabolisms are able to process alcohol at a more efficient rate than those with slower metabolisms. Metabolism can be influenced by certain genetic factors, but also by diet, sleep, exercise, and stress. A faster metabolism is also associated with less body fat, and more lean mass – both of which are known to improve alcohol processing and absorption.
- Sex: In many cases there are differences in how long alcohol stays in the body of a male versus that of a female. Since females have less water and more fat compared to men, alcohol stays in their system longer (on average). In part, this is why women can reach a higher blood-alcohol concentration than men of relatively equal weight after the same number of drinks.
- Stress level: There is some evidence to suggest that alcohol absorption can be altered based on your stress level and mood. Individuals that are highly stressed have completely different neurophysiological activation than those who are relaxed prior to drinking. There is reason to believe that the body may have slowed alcohol absorption if under significant stress.
Note: A common myth is that individuals with a “high tolerance” to alcohol are able to clear it more quickly from their systems, reducing blood-alcohol concentrations. Although individuals with a greater tolerance to alcohol may not experience the same degree of intoxication as non-tolerant individuals, tolerance does not affect blood alcohol concentration. Those with a high tolerance are more likely to experience deleterious alcohol withdrawal symptoms than those with a lower tolerance.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/18090653
- Source: http://pubs.niaaa.nih.gov/publications/arh301/3-4.htm
How is alcohol absorbed, metabolized, and excreted from the body?
When you ingest alcohol, it is absorbed by your gastrointestinal tract, or more specifically, your small intestine (due to its large surface area). It is estimated that approximately 80% of alcohol is absorbed by your small intestine, but if you are in a fasted state (i.e. have an empty stomach), a smaller percentage (20%) may be absorbed via the stomach lining. Since alcohol has a high affinity for water, it is most commonly found within bodily tissues that contain water (e.g. muscle) and less likely to be found within tissues containing minimal water (e.g. fat).
Following absorption via the small intestine, the alcohol is shuttled to the bloodstream, and ultimately dispersed throughout the entire body. The liver is responsible for metabolizing and excreting approximately 95% of the alcohol that an individual consumes. The remaining 5% of alcohol consumed is eliminated from the body through things like: breath, feces, urine, saliva, and sweat.
Your body metabolizes alcohol primarily via enzymes such as: ADH (alcohol dehydrogenase) and ALDH (aldehyde dehydrogenase). The ADH enzyme is known for breaking down a majority of alcohol into acetaldehyde, which eventually is further broken down into acetate (or acetic acid), and from acetate is metabolized into water and carbon dioxide. These molecules function primarily within the liver and the stomach, but can be found within other tissues.
After it has been fully metabolized into water and carbon dioxide, it is efficiently cleared from the system. If an individual consumed a large amount of alcohol (such as via binge drinking), the enzymes CYP2E1 (cytochrome P450 2E1) and catalase will aid in the metabolic process. CYP2E1 enzymes are concentrated primarily within the liver, whereas catalase is abundant throughout the human body.
It should also be noted that a relatively minimal amount of alcohol is thought to be eliminated by interactions with fatty acids following formation of fatty acid ethyl esters (FAEEs). Healthy individuals metabolize alcohol at a consistent rate of approximately .015% BAC per hour. The duration over which it takes alcohol to get eliminated from your system largely depends upon your peak blood-alcohol concentration, as well as when you stopped drinking.
A person who reached a BAC of 2.0 will take much longer to metabolize and eliminate alcohol from their system than a person who reached a BAC of 1.0 (assuming both stopped drinking at the same time). For this reason, it is recommended to minimize likelihood of a high BAC (avoid binging and high ABV drinks) and quit drinking as soon as possible (to give your body time to metabolize alcohol).
- Source: http://pubs.niaaa.nih.gov/publications/AA72/AA72.htm
Types of Alcohol Testing
If you get pulled over driving and a law enforcement agent suspects that you’ve been drinking, you’ll likely be subject to alcohol testing. This testing is generally conducted with a breathalyzer, but more complex testing such as blood tests and/or urine tests may be administered.
Blood tests: Those subject to blood alcohol testing will first need to give consent to have their blood drawn. However, if you refuse to take a blood test as requested by a law enforcement agent – you could have your license suspended and/or revoked. Research suggests that individuals who refuse blood alcohol tests tend to receive higher fines and spend more time in jail than those who accept them.
Should you agree to have your blood drawn, a sample of approximately 4 milliliters will be collected by a vacutainer. The vacutainers contain both sodium-fluoride and potassium-oxalate to minimize likelihood of contamination. Should an expired vacutainer be utilized to collect a blood sample, test results could be compromised.
Assuming a non-expired vacutainer is used to collect the blood sample, and no laboratory testing errors are made (e.g. mix-ups), results will be more accurate than breath-based or urinary assays. Blood samples will accurately reveal a person’s blood-alcohol concentration (BAC). As a result, blood testing is most commonly used among acutely intoxicated individuals and/or those suffering from chronic alcoholism. Alcohol can show up in the blood for up to 12 hours following a person’s last drink.
Breathalyzer tests: Breathalyzer tests are commonly utilized by law enforcement agents to determine whether an individual is “over the legal limit” (0.08 BAC) for driving. Breathalyzer testing remains the most popular way to test for alcohol intoxication due to the fact that it is non-invasive, accurate, and produces nearly instantaneous results. When an individual “breathes” into a breathalyzer, alcohol passes through alveoli air sacs simultaneously as blood flows through vessels within the lungs, and the alcohol is detected via a person’s “breath.”
While not quite as accurate as a blood test, breathalyzer tests [derived from fuel cell sensor technology] are considered accurate enough for DUI prosecution. These tests generally verify presence of alcohol and determine the degree of intoxication. Alcohol can be detected in breathalyzer tests for up to 24 hours following consumption – depending on peak BAC and time since a person’s last drink.
Due to portability, ease-of-use, and accuracy – many people have purchased their own breathalyzers to know whether they are below the BAC threshold of 0.08 and are “legal” to drive. In rare cases, results on a breathalyzer test may be subject to inaccuracies as a result of a particular environmental setting (e.g. presence of volatile fumes) and/or programming.
Urine tests: In rare cases, a fresh urine sample may be collected from an individual to determine whether they’ve been drinking. Urine testing is considered both accurate and reliable when conducted within a small window following ingestion. It is estimated that alcohol can be accurately detected within 10 to 12 hours via standard methods, or 3 to 5 days if testing for EtG (Ethyl Gluconoride) metabolites is conducted; EtG metabolites can stay in your system for up to 80 hours.
If standard urine tests (non-EtG) are conducted outside a 12 hour window, urine testing may be subject to inaccuracies. It has been discovered that urine tests may portray abnormally high or low levels of alcohol relative to actual blood-alcohol concentrations. In other words, a urine sample may depict that an individual has a BAC of 1.0, when in reality their BAC is 0.07; vice-versa also applies.
Urine testing is problematic in that it is difficult to perform at the scene of a car accident (whereas a breathalyzer test is easily administered), and even if samples could be collected, it would take time to get them properly analyzed. The time lag between collection and laboratory analysis has been known to skew results of alcohol concentrations within urine. Furthermore, it may take nearly 2 hours before alcohol appears in a urine sample and up to 24 hours before it is completely eliminated from a person’s system.
The fact that urine tests may not accurately prove whether an individual is under the influence of alcohol at a specific time, they are seldom used at the scene of an incident. EtG urine tests are most commonly used among individuals prohibited from drinking alcohol (by the legal system or employers) to determine whether they’ve been drinking alcohol within the past several days. Should the test detect the presence of EtG, it can be concluded that the individual hasn’t remained sober.
Hair tests: Another less common way to test for alcohol is via hair samples. Hair samples at a length of 3 cm to 6 cm are typically taken from a person’s scalp and sent to a lab to be assessed for the presence of EtG (Ethyl Gluconoride) and FAEE (fatty acid ethyl esters), metabolites that linger in your system following consumption of alcohol. Although hair testing doesn’t determine whether someone is currently “under the influence” (or blood-alcohol content), it can accurately reveal whether someone has consumed alcohol within the past 90 days.
In other words, this test will determine whether someone has ingested alcohol within the past several months or remained sober. An alcohol hair test is commonly administered by legal officials and/or employers to individuals with a history of DUIs who are prohibited from drinking alcohol. Hair testing may utilized in conjunction with urine testing to verify presence of metabolites EtG and FAEE.
Saliva tests: There are various alcohol saliva tests that are approved by the DOT (Department of Transportation) and waived by the CLIA (Clinical Laboratory Improvement Amendments). Such tests are generally intended to accurately determine the quantity of alcohol within an individual’s saliva. Saliva testing for the presence of alcohol is generally capable of yielding results within 2 to 5 minutes and can determine whether an individual has used alcohol the past day.
Saliva samples are easy to collect, a simple swab of the inner cheek is the most common way to attain a sample. In addition, saliva testing is less invasive than urine testing and is able to provide an accurate approximation of blood-alcohol content; the concentration of alcohol in saliva is generally similar to the concentration of alcohol within blood. As a result, saliva tests serve as a viable alternative to breath and blood tests.
How to Minimize Peak Blood Alcohol Concentrations
The most obvious way to maintain a low blood-alcohol concentration (BAC) is to avoid consuming too much alcohol (especially over a short-duration). Since we know that your BAC is likely to drop by 0.015 every hour, and you likely want to remain below the legal limit (0.08), your best bet is to avoid going above a BAC of 0.08 in the first place. Below are some tips that may help you metabolize alcohol and/or maintain a lower BAC.
- Avoid binge drinking: Those who consume copious amounts of alcohol over a short duration with the intention of becoming intoxicated (i.e. binge drink) experience high BACs than those who avoid binge drinking. The higher your BAC, the longer it takes to metabolize alcohol. Since your liver is only capable of metabolizing 1 average sized drink per hour, it is recommended to avoid binge drinking to avoid a BAC spike and putting a toxic burden on your liver.
- Choose low ABV drinks: Many people underestimate the strength of the alcohol that they consume. Mixed-drinks containing whiskey, gin, or vodka – generally contain a markedly greater amount of alcohol-by-volume (ABV) compared to a standard 12 oz beer. In effort to minimize your BAC and stay under the legal driving limit of 0.08, it is recommended to choose the lowest ABV drinks.
- Eat food: It is always smart to eat something (especially protein-rich foods) prior to drinking and/or while drinking. If you have food in your stomach, it will slow the processing of alcohol – whereas drinking alcohol on an empty stomach results in more rapid processing. An individual who has consumed food prior to drinking will attain a peak BAC within 30 minutes to 2 hours of drinking, whereas someone who has eaten may attain a peak BAC between 1 and 6 hours of drinking.
- Non-alcoholic beverages: Many people go out drinking and assume they need to drink nothing but alcohol for the entire night. It is important to consider mixing things up with a non-alcoholic beverage (e.g. N/A beer) to avoid a high BAC. Avoiding a high BAC by drinking more non-alcoholic beverages will help your body eliminate alcohol quicker because you will have consumed less alcohol.
- Know yourself People often get caught up in “keeping up” with friends, when failing to consider that your ability to handle alcohol is often based on your body size, sex, and other personal factors (such as whether you’re taking any medications). If you are a 120 lb female, it would make no sense to try and “keep up” with a 300 lb male drinking companion; your BAC would be much higher than his with the same amount of drinks. Limit yourself to fewer drinks if you are smaller, and beware of any contraindications associated with alcohol and medications.
- Stay in shape: Staying in good physical shape can help your body process alcohol due to the fact that it reduces fat, adds lean muscle, and keeps your metabolism high. Individuals with high fat and low muscle don’t process alcohol as efficiently and may attain a higher BAC within a shorter duration from fewer drinks – compared to those with low fat and high muscle. Lifting weights and engaging in cardio when you’re not drinking can be helpful.
- Set limits: Prior to a night of drinking, it is often helpful to set limits and tell these limits to drinking partners (or friends). By setting personal limits, you should have an easier time avoiding excess alcohol consumption. Most people set limits of drinking more than a certain number of beers per hour. Your personal limit should be based on your body mass (height / weight) and sex (male vs. female).
- Sip slowly: It is important to avoid “gulping” or “chugging” alcohol if you want to maintain a low BAC. Sipping your drink slowly will help you avoid getting caught up in binge drinking and increase the likelihood that you’ll adhere to predetermined limits. Slow sipping means that alcohol is entering your body at a slower rate. To maximize the benefit from “sipping slowly,” increase the time intervals between sips, and decrease the amount of alcohol per sip. Take time to appreciate and enjoy the taste of your beer as opposed to drinking it for the sake of getting drunk.
What’s the longest duration that alcohol has stayed in your system?
Assuming you’re a regular drinker or former heavy drinker, share a comment mentioning the longest time over which you believe alcohol has stayed in your system. To help others understand your scenario, provide further details such as: how many drinks you had, the ABV content of the drinks, your body mass, and more. Were you able to verify your blood alcohol concentration via some sort of testing such as: blood testing, breathalyzer testing, or urine testing?
Keep in mind that a reliable way to determine whether your blood alcohol concentrations have dipped below the legal limit (0.08) is to purchase a highly-accurate breathalyzer and test yourself. The price of even the most expensive breathalyzers may be well worth it if they’re able to help prevent a DUI. Always test yourself to verify that you are below the legal limit before operating a motor vehicle (or any heavy machinery). If you aren’t sure whether alcohol is still in your system – don’t risk driving.