Alcohol is detectable in your system anywhere from a few hours to several weeks, depending on the type of test. Your liver clears alcohol from your blood at a relatively fixed rate of about 0.015 to 0.020 percent blood alcohol concentration (BAC) per hour, which works out to roughly one standard drink every 60 to 90 minutes. But traces of alcohol’s byproducts linger much longer than the alcohol itself.
How Your Body Processes Alcohol
Your liver does the heavy lifting. An enzyme called alcohol dehydrogenase breaks alcohol down into acetaldehyde, a toxic compound and known carcinogen. A second enzyme then converts acetaldehyde into acetate, which your body breaks down further into water and carbon dioxide for easy elimination. A small percentage of alcohol leaves your body unchanged through your breath, sweat, and urine, which is why a breathalyzer works.
This process is essentially a conveyor belt with a fixed speed. Your liver can only handle so much at once, so drinking faster than your body can metabolize simply raises your BAC higher and keeps alcohol in your system longer. A study of 103 intoxicated emergency department patients found the average blood alcohol clearance rate was about 20 mg/dL per hour, with significant individual variation. Some people cleared alcohol nearly three times faster than others.
What Counts as One Drink
A standard drink in the United States contains about 14 grams of pure alcohol. That equals a 12-ounce beer at 5% alcohol, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of liquor at 40%. Many cocktails and craft beers contain significantly more than one standard drink, which means your actual intake is often higher than you think.
Detection Windows by Test Type
Different tests look for different things, and their detection windows vary dramatically.
- Blood and breath: Alcohol itself is detectable in blood and on a breathalyzer only while your BAC is above zero. For most people, this means roughly one hour per standard drink consumed. Three drinks at dinner would typically clear from your blood in about three to four hours, though individual metabolism varies.
- Urine (standard): A conventional urine test picks up alcohol for about 12 to 24 hours after your last drink.
- Urine (EtG): Ethyl glucuronide tests detect a metabolic byproduct of alcohol, not alcohol itself. The typical detection window is 24 to 72 hours, though heavy drinking can extend that to 80 hours. A result above 1,000 ng/mL generally points to same-day drinking or heavy drinking the previous day, while results between 100 and 500 ng/mL could reflect light drinking a few days earlier or even incidental exposure to alcohol-based products like hand sanitizer or mouthwash.
- Blood (PEth): Phosphatidylethanol is a biomarker that forms only when alcohol is present in the bloodstream. It’s detectable for up to four weeks after drinking and is primarily used to identify moderate or heavy alcohol use over that period. It cannot reliably distinguish between abstinence and very light drinking.
- Hair: Hair follicle tests can detect alcohol metabolites for up to 90 days, though they reflect patterns of use rather than single drinking episodes.
Factors That Speed Up or Slow Down Clearance
Your liver’s processing speed isn’t something you can meaningfully control in the short term. Coffee, cold showers, and food won’t sober you up faster once alcohol is already in your bloodstream. Food eaten before or during drinking slows absorption into the blood, which lowers your peak BAC, but it doesn’t change how quickly your liver works through what’s already there.
Body weight and composition matter because alcohol distributes through body water. A larger person with more water volume will generally reach a lower BAC from the same number of drinks. Women typically reach higher BAC levels than men of similar weight because of differences in body water percentage and enzyme activity.
Regular heavy drinking can actually increase one of the backup enzyme pathways your liver uses to process alcohol, which is why chronic drinkers sometimes appear to “tolerate” more. This isn’t a health advantage. It means the liver is under greater stress and producing more harmful byproducts in the process.
Does Liver Disease Change the Timeline?
You might expect liver disease to dramatically slow alcohol clearance, but the picture is more nuanced than that. Research comparing people with alcoholic cirrhosis to healthy subjects found that the liver’s maximum processing capacity for alcohol was not significantly different between the two groups. Chronic alcohol exposure appears to ramp up enzyme production even in a damaged liver, partially compensating for lost liver tissue.
That said, a cirrhotic liver has distorted blood vessel structure and internal shunting, meaning blood can bypass the parts of the liver that would normally filter it. The practical result is less efficient elimination even when the remaining liver cells are working hard. People with significant liver disease should not use general clearance estimates as a reliable guide.
Practical Estimates for Common Scenarios
Using the average clearance rate of about 0.015 BAC per hour, here are rough timelines for alcohol leaving your blood completely. These assume you stopped drinking at the times listed and your BAC peaked around the values shown.
- Two drinks over dinner: BAC peaks around 0.04 to 0.05. Alcohol clears from blood in roughly 3 to 4 hours.
- Four drinks over two hours: BAC peaks around 0.08 to 0.10. Expect 5 to 7 hours before your blood is clear.
- Heavy night out (8+ drinks): BAC can peak at 0.15 or higher. You could still have measurable blood alcohol 10 or more hours later, well into the next morning.
These are estimates for an average-sized adult. Your actual clearance depends on your weight, sex, liver health, and individual enzyme activity. If you’re facing an EtG urine test, the window extends well beyond when you feel sober. Even moderate drinking can produce a positive result two to three days later.