Alcohol is detectable in your system for anywhere from 12 hours to several months, depending on the type of test. Your body eliminates alcohol from your blood at a fairly steady rate of about one standard drink per hour, but byproducts of that process linger much longer in urine, saliva, and hair.
How Fast Your Body Processes Alcohol
Your liver does roughly 95% of the work breaking down alcohol. It processes it at an average rate of about 15 mg per 100 mL of blood per hour, which works out to roughly one standard drink every 60 to 90 minutes. That rate holds fairly steady regardless of how much you drink. Your liver can’t speed up just because there’s more alcohol in your system, so the more you consume, the longer total clearance takes.
A standard drink in the United States contains about 14 grams of pure alcohol. That’s 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 drinks people actually pour are larger than these, so two glasses of wine at dinner could easily equal three or four standard drinks.
Detection Windows by Test Type
Different tests look for different things. Some measure alcohol itself, while others detect metabolic byproducts your body produces while breaking it down. Here’s how the timelines compare:
- Blood and breath: Up to 12 hours after your last drink. These tests measure actual alcohol circulating in your system and are the standard for roadside stops and emergency rooms.
- Saliva: Up to 24 hours. Oral fluid tests are increasingly common in workplace screening because they’re easy to administer.
- Urine (standard ethanol test): Roughly 12 to 24 hours for alcohol itself.
- Urine (EtG metabolite test): Up to 5 days after heavy drinking, depending on the sensitivity threshold. At the most sensitive cutoff (100 ng/mL), this test catches 85% of even light drinking within one day and still picks up 79% of heavy drinking episodes five days later. At a higher cutoff (500 ng/mL), detection mostly captures heavy drinking from the previous day.
- Hair: 3 to 6 months. Hair tests look for the same EtG metabolite and are used when a long look-back window is needed, such as in custody cases or professional licensing reviews.
If you’re facing a specific test, the type matters enormously. A breath test the morning after a few drinks may come back clean, while a urine EtG test ordered two days later could still flag positive.
Why It Takes Longer for Some People
The “one drink per hour” rule is an average, and individual variation is significant. Elimination rates range from about 10 to 35 mg/100 mL per hour across the population. Several factors push you toward the slower or faster end of that range.
Body Composition and Sex
Women typically reach higher blood alcohol levels than men after drinking the same amount, even when adjusted for body weight. The main reason is body water. Alcohol dissolves in water, and women on average carry proportionally less body water and more body fat than men of the same weight. Less water means the same number of drinks produces a higher concentration of alcohol in the blood. Women may also have a higher liver volume relative to lean body mass, which can partly offset this effect during elimination, but the initial peak is still higher, and total clearance takes longer.
Genetics
Your genes determine how efficiently the enzymes that break down alcohol function. One well-studied variant involves a key enzyme responsible for clearing acetaldehyde, the toxic intermediate compound your liver produces while processing alcohol. People who carry one copy of this genetic variant have noticeably slower clearance rates. Those who carry two copies can have blood acetaldehyde levels 18 times higher than people without the variant after the same amount of alcohol. This mutation is particularly common in people of East Asian descent and is responsible for the facial flushing, nausea, and rapid heartbeat some people experience after even small amounts of alcohol.
Liver Health
Because your liver handles nearly all alcohol metabolism, any condition that reduces liver function (fatty liver disease, hepatitis, cirrhosis) slows the process. Chronic heavy drinking itself damages the liver over time, creating a cycle where the organ responsible for clearing alcohol becomes progressively less capable of doing so.
Does Eating Help?
Eating before or while drinking is one of the few things that genuinely changes the experience, but not in the way many people assume. Food in your stomach slows the rate at which alcohol is absorbed into your bloodstream, which means your blood alcohol level rises more gradually and peaks lower. This is why drinking on an empty stomach hits harder and faster.
However, research shows the total time to reach zero blood alcohol is essentially the same whether you eat or not. In one study, the time to full elimination was 5.01 hours with food and 5.05 hours without. Eating smooths out the curve but doesn’t shorten the overall timeline. The alcohol still has to be processed, and your liver works at roughly the same pace either way.
What Doesn’t Speed Things Up
Coffee, cold showers, exercise, and “sweating it out” do not accelerate alcohol metabolism. Your liver processes alcohol at a fixed enzymatic rate that these interventions cannot change. Coffee may make you feel more alert, but your blood alcohol level stays exactly where it would have been without it. The only thing that reliably clears alcohol from your system is time.
Practical Timelines
To give you a rough sense of what to expect: if you have four standard drinks over two hours and then stop, your blood alcohol level will peak shortly after your last drink and take approximately 4 to 6 hours to return to zero. A heavier night of 8 to 10 drinks could mean alcohol is still present in your blood 10 to 12 hours later, well into the next morning.
For urine EtG testing, the math is different entirely. Even moderate drinking on a Friday night can produce a positive result on a Monday test at sensitive cutoff levels. Heavy drinking extends that window further. If you know you’ll be tested, the only reliable strategy is abstinence for a sufficient period before the test, matched to whatever type of test you’re facing.