Your liver processes about 90% of the alcohol you drink, breaking it down at a roughly fixed rate of one standard drink per hour. The other 10% leaves your body through sweat, breath, and urine. But “how long alcohol stays in your system” depends on what you mean: the buzz you feel, the alcohol in your blood, or the traces a test can detect days or even months later.
How Your Liver Breaks Down Alcohol
When you drink, alcohol enters your bloodstream through the stomach and small intestine, then travels to the liver. There, your liver uses a two-step process to neutralize it. First, an enzyme called alcohol dehydrogenase converts ethanol into acetaldehyde, a toxic compound responsible for many of the unpleasant effects of drinking. A second enzyme then converts acetaldehyde into acetate, which your body can safely use for energy or eliminate.
This process is the liver’s primary job when alcohol is present, and it takes priority over other metabolic tasks. One standard drink in the United States contains about 14 grams of pure alcohol, roughly the amount in a 12-ounce beer, a 5-ounce glass of wine, or a 1.5-ounce shot of liquor. Your liver can process approximately one of these per hour. If you drink faster than that, the excess alcohol circulates through your body, raising your blood alcohol concentration (BAC) until the liver catches up.
What Affects How Fast You Process Alcohol
That “one drink per hour” figure is an average, and several factors push your personal rate higher or lower.
Body size and composition play a major role. A larger person with more muscle mass and body water has more volume to dilute alcohol, resulting in a lower BAC from the same number of drinks. Fat tissue does not absorb alcohol well, so people with a higher body fat percentage tend to have more concentrated alcohol in their blood.
Biological sex matters too. Women generally absorb more alcohol and take longer to process it than men, even at the same body weight. This is partly because women tend to have less body water and more body fat relative to their size, and partly because of differences in enzyme activity and hormones. The result: after drinking the same amount, women typically reach a higher BAC and stay at that level longer.
Genetics also play a part. About 30% of people with East Asian ancestry carry a variant of the ALDH2 gene that slows the breakdown of acetaldehyde, the toxic intermediate step. Carriers of this variant often experience facial flushing, nausea, and rapid heartbeat after even small amounts of alcohol. The variant also reduces the overall rate of alcohol metabolism, meaning alcohol and its byproducts linger longer in their systems.
How Food Changes the Timeline
Eating before or while you drink slows the rate at which alcohol reaches your small intestine, where most absorption happens. A full stomach doesn’t prevent absorption entirely, but it spreads it out over a longer period. This means your BAC rises more gradually and peaks at a lower level than it would on an empty stomach. It also gives your liver more time to keep pace with the incoming alcohol.
The type of food matters somewhat. Meals with protein and fat slow stomach emptying the most, creating a longer buffer. Drinking on a completely empty stomach, by contrast, allows alcohol to pass quickly into the small intestine. Peak BAC can arrive in as little as 30 minutes on an empty stomach versus an hour or more after a substantial meal.
Detection Windows by Test Type
The alcohol itself clears your bloodstream relatively quickly, but its metabolic byproducts stick around much longer. Here’s how different tests compare:
- Breath: A standard breathalyzer detects alcohol for roughly 12 to 24 hours after your last drink, depending on how much you consumed.
- Blood: Alcohol is detectable in blood for about 6 to 12 hours. Blood tests measure current impairment and are commonly used in medical and legal settings.
- Urine (standard): A basic urine test picks up alcohol for about 12 to 24 hours.
- Urine (EtG): A more sensitive urine test looks for ethyl glucuronide, a metabolite your body produces when processing alcohol. After a few drinks, EtG can show up in urine for up to 48 hours. With heavier drinking, it can remain detectable for 72 hours or longer. This test is commonly used in probation, treatment programs, and workplace monitoring.
- Hair: Hair follicle tests can detect alcohol use for 1 to 6 months, making them useful for evaluating drinking patterns over time rather than recent use.
These windows are approximate. The more you drink in a session, the longer every test type will remain positive. Someone who had two beers will clear all traces far sooner than someone who had eight.
Why You Can’t Speed It Up
Coffee, cold showers, exercise, and food after drinking are all popular ideas, but none of them increase the rate at which your liver metabolizes alcohol. Coffee might make you feel more alert, but your BAC stays the same. Exercise increases breathing rate slightly, but since only about 10% of alcohol leaves through breath and sweat combined, the effect is negligible.
The liver’s enzyme system works at a largely fixed pace. You can slow absorption down (by eating beforehand), but once alcohol is in your blood, you’re waiting for your liver to do its job. For most people, BAC drops by roughly 0.015 per hour. If you stop drinking at a BAC of 0.08 (the legal limit for driving in most U.S. states), it takes about five and a half hours to reach zero.
What This Means in Practice
If you had three or four drinks over a couple of hours at dinner, you likely still have measurable alcohol in your blood when you wake up the next morning. Many people underestimate this. A night of heavier drinking that ends at midnight could leave you above the legal driving limit well into the following morning.
For testing purposes, the relevant question is which type of test you’re facing. A standard breath or blood test reflects the last several hours. An EtG urine test looks back two to three days. A hair test covers months. Each one captures a different window, and knowing the distinction helps you understand what the test is actually measuring.