Urine tests can determine whether you have consumed alcohol within the last 24 hours.
Alcohol has a relatively short life span in the body, but a urine test can detect alcohol long after its effects wear off.
Urine tests can accurately detect ethanol and its byproducts 12 to 24 hours after you have a drink. The exact detection period depends on the type of urine alcohol test you take.
Ethanol urine tests can detect alcohol consumption within the last 12 hours, while ethyl glucuronide (EtG) tests and ethyl sulfate (EtS) tests can typically help detect alcohol consumption within the last 24 hours.
Although some EtG and EtS tests may detect alcohol up to 80 hours after your last drink, there’s a higher chance of a false negative after 24 hours.
EtG tests are a common way to test for alcohol consumption. The following chart shows how likely it is for urine alcohol levels to show up in EtG tests based on how much alcohol you consume and how much time passes after your last drink.
This chart is based on a positive cut-off threshold of 100 nanograms of EtG per milliliter. In other words, it assumes you’ll test positive if the test detects more than 100 nanograms per milliliter.
However, criminal courts generally use a threshold of 500 nanograms per milliliter.
| Hours (hrs) | Light (1–4 drinks) | Moderate (5–9 drinks) | Heavy (10+ drinks) |
|---|---|---|---|
| 1–12 hrs | likely | likely | likely |
| 12–24 hrs | possible either way | likely | likely |
| 36–48 hrs | unlikely | possible either way | likely |
| 48–60 hrs | unlikely | unlikely | possible either way |
| 60–72 hrs | unlikely | unlikely | fairly unlikely |
| 72–80 hrs | unlikely | unlikely | unlikely |
Urine alcohol tests can help doctors determine whether you have consumed alcohol within a certain time. It’s possible to test positive for alcohol consumption even if you’re not currently intoxicated.
Consuming a large amount of alcohol might produce positive results on a urine test for longer than consuming a single drink. However, urine alcohol tests can’t accurately detect how much you have had to drink.
Your urine flushes alcohol out of your system. During the first few hours after drinking, ethanol may be detectable in your urine and other bodily fluids.
Tests may also detect alcohol by measuring metabolites of alcohol, like EtG or EtS. Your body makes metabolites while it processes alcohol.
Metabolites stay in your system for longer than actual alcohol does, which is why tests that measure alcohol metabolites have a longer period of detection.
Urine
For urine alcohol tests, the period of detection depends on the type of test you take.
- Ethanol urine tests: 12 hours
- EtG urine tests: 24 to 72 hours
- EtS urine test: 24 to 72 hours
Although tests can vary in sensitivity, experts generally only consider EtG and EtS tests accurate within the first 24 hours. They may accurately detect alcohol use for a longer period.
Still, after 24 hours, there’s a higher chance of a false negative. In other words, the result will be negative even if you have consumed alcohol.
Saliva
Saliva tests can measure blood alcohol content (BAC). They may detect alcohol consumption for a maximum of 24 hours after you’ve consumed alcohol.
After 24 hours, your body usually metabolizes alcohol, making it near-impossible to detect in your saliva.
Blood
Blood tests can also detect recent alcohol consumption. Certain blood alcohol tests measure your BAC, while others look for biomarkers of alcohol consumption.
The detection periods differ from test to test:
- Traditional blood alcohol tests measure your BAC and detect alcohol consumption within the last 12 hours.
- EtG and EtS blood tests detect alcohol in your body up to 24 hours after your last drink.
- Carbohydrate-deficient transferrin tests can identify regular heavy drinking.
- Phosphatidylethanol (PEth) blood tests detect drinking in the previous 1 to 3 weeks, but your PEth levels may be high for longer after prolonged heavy drinking.
Breath
A breathalyzer can usually detect alcohol consumption within the past 4 to 6 hours. It may test positive as long as 24 hours after your last drink.
A breathalyzer doesn’t just detect whether you’ve consumed alcohol. It can also measure your BAC, which correlates to how much alcohol you’ve had.
Many factors affect how quickly you
- Age: Teenagers, young adults, and older adults tend to
eliminate alcohol slower than people in their late 20s to 50s. - Tolerance: If you frequently drink heavily, you might metabolize it faster.
- Exercise: You might eliminate alcohol faster if you exercise.
- Food: If you’ve eaten recently, you may metabolize alcohol faster.
- Health: If your kidneys or liver don’t function as well as they should, you may metabolize alcohol slower.
- Time of day: People tend to metabolize alcohol faster later in the day.
The average metabolic rate to remove alcohol is about one drink per hour, but the above factors might affect that rate slightly.
It’s almost impossible to sober up quickly, but you can help your body eliminate alcohol faster in several ways.
You can try the following to metabolize alcohol faster:
- Eat a substantial meal.
- Drink plenty of water.
- Do some light exercise.
- Urinate frequently.
In general, the only thing that reliably reduces your BAC is time. Give yourself time to sober up and avoid behavior that may have harmful effects if you’ve recently had alcohol, like driving.
Urine tests can detect whether you’ve recently had alcohol. In general, they can be accurate for 12 to 24 hours, depending on the nature of the test.
Certain alcohol tests — particularly blood tests — can also help determine heavy and prolonged drinking.
Sian Ferguson is a freelance health and cannabis writer based in Cape Town, South Africa. She’s passionate about empowering readers to take care of their mental and physical health through science-based, empathetically delivered information.
