How long the detection window lasts, though, is dependent on different factors, such as your age, weight, gender, health — both mental and physical — the amount and type of alcohol consumed, and whether or not you drink on a full or empty stomach. But, generally, you can expect alcohol to be detectable in your urine anywhere from 12 hours to three days after you’ve had a drink.
Urine tests can detect alcohol or ethanol itself or certain alcohol byproducts. The type of urine testing can also make a difference in whether the alcohol you consume is still detectable more than one day later.
What Happens to Alcohol in the Body?
Alcohol leaves the body in different ways after it is consumed. Some of the alcohol a person consumes is absorbed into the bloodstream from the stomach. The rest is absorbed from the small bowel.
Most of the alcohol a person drinks — about 90 to 95 percent — makes its way to the liver where it is broken down or metabolized. Liver cells convert the alcohol into acetaldehyde, a toxic chemical that causes hangover symptoms, and then to acetate.
Acetate converts to carbon dioxide and water and eventually leaves the body.
When a person ingests greater amounts of alcohol than the liver can sufficiently process within an hour, the blood will hold the substance. This is commonly referred to as a person’s blood alcohol concentration or BAC. A person’s BAC is easily detectable with the use of a breathalyzer.
But 5 to 10 percent of the alcohol will not make its way into the liver. It will instead leave the body through the lungs, sweat, and urine.
Alcohol Detection in Urine
Only about 1 to 2 percent of the alcohol a person drinks leaves the body in their urine. The ethanol in alcohol can be detected in a person’s urine within an hour of drinking. This typically remains the case for up to 12 hours after the alcohol is consumed. This timeframe can vary based on a number of individual factors.
Factors Affecting Alcohol Detection
Many different factors can affect how alcohol is absorbed in a person’s body, as well as how it is processed and thereby, how long it might be detectable in their urine.
Gender, body fat and menstruation
Women have less of the enzyme dehydrogenase, used by the body to break down alcohol in the stomach. Women also have higher percentages of body fat and less water weight than men. These all affect a person’s BAC. This means that women — all other factors equal or relative — typically reach higher levels of intoxication than men even when drinking the same amount of alcohol. Women will also become more intoxicated when drinking just before their period since hormones play a role in a person’s BAC as well. Studies show, however, that women seem to eliminate alcohol from their bodies faster than men.
Older people are more likely to become intoxicated faster. This is due to normal age-related changes in their bodies, including a slowing metabolism, loss of muscle tissue and decrease in water weight.
Type of alcohol consumed
Drinks with higher alcohol concentrations or greater percentages of alcohol by volume (ABV), such as spirits and some wines, are generally absorbed by the body faster, leading to more significant levels of intoxication. Carbonated or sparkling drinks, such as champagne, or mixing liquor with soda can have the same effect.
Full or empty stomach
Drinking on a full stomach will slow the body’s absorption of the alcohol. Conversely, drinking on an empty stomach will speed the effects of alcohol and cause a person to reach their peak BAC more quickly — sometimes within just 30 minutes after consumption depending on the amount of alcohol ingested. Foods higher in protein are a person’s best choice to stave off alcohol’s effects.
Individual alcohol tolerance
Genetics can make some people’s bodies more or less efficient at processing alcohol. When certain liver enzymes, such as ADH and ALDH, do not work sufficiently, their bodies are unable to process alcohol normally. These people might experience a sudden rise in their acetaldehyde levels after drinking alcohol. This reaction can cause undesirable side effects, including a flushed face, reddening of the skin in the face or neck especially, dizziness, hot sensations, nausea or vomiting, and heart palpitations.
Overall health – physical and mental
Depression, anxiety, and alcohol don’t always mix well. While small amounts of alcohol can provide a person with a brief euphoria, larger amounts can actually worsen a person’s mood. Someone already suffering from a mood or mental health disorder might exacerbate their symptoms by drinking. The body’s stressful state may also change the way and rate at which the body processes the alcohol by causing a change in the stomach’s enzymes.
Likewise, someone with an existing health condition, such as heart problems, Type 2 diabetes, liver damage or kidney problems, may process alcohol at a different or slower rate than the average healthy person. Conditions affecting the liver might make metabolizing alcohol difficult, if not entirely impossible, for the body to accomplish.
Accuracy of Urine Testing for Alcohol
Urine testing is a popular, inexpensive and less invasive way to detect alcohol in a person’s system. And since alcohol can sometimes remain detectable in the urine for up to two days after it is ingested, it is an accurate indicator of a person’s alcohol consumption.
But the amount of alcohol present in the urine is typically about 1.33 times greater than the amount of alcohol found in the bloodstream. This can sometimes result in tests that conclude a person drank more alcohol than what was realistically consumed. It is thereby a good rule of thumb to have at least two urine samples collected about 30 minutes to one hour apart for more accurate results.
Detection of Alcohol Byproducts in Urine
Alcohol itself in urine has a relatively short detection window — usually less than a day. But alcohol byproducts, such as ethyl glucuronide (EtG), can be detected in a person’s urine for up to three days after they have consumed their last drink.
Other lab tests might also test the urine for ethyl sulfate (EtS). EtS is another type of metabolic substance or metabolite that signals the presence of alcohol in a person’s system.
These tests are often more reliable than traditional urine testing and allow for a lengthened detection window, so they are often the testing method of choice by courts to enforce probationary requirements and by rehab programs to ensure effective treatment and identify a possible relapse.
But these tests are not more commonly used in the place of traditional urine testing because they have drawbacks.
There are several disadvantages to EtG/EtS urine testing, including:
- Higher cost
- Inability to determine the amount of alcohol consumed
- Inability to differentiate between ethanol from alcoholic drinks and alcohol from other products, such as an over-the-counter cough and cold medicines, some mouthwashes, body sprays, and hand sanitizers
False Positives and EtG/EtS Urine Testing
Other problems with EtG/EtS urine testing is that these tests have been found to sometimes yield false positives, which can have serious adverse impacts on a person.
A 2006 that study evaluated the levels of EtG in the urine of participants who had used a commercially available mouthwash containing 12 percent ethanol found that incidental exposure to ethanol from using mouthwash as directed can result in a positive urine screen.
Study authors concluded that “EtG formed from the alcohol may be present in the urine samples of individuals whose only source of alcohol exposure was the use of such mouthwash” and suggested that all positive EtG results be reviewed by a qualified health care professional.
Failure to detect alcohol more than 26 hours after it was consumed was found to be another problem of an EtG urine test, according to a 2007 study published by Oxford University Press in the journal Alcohol and Alcoholism.