In This Article
What is an EtG Test?
EtG tests are a specific type of drug test that shows if someone has recently consumed alcohol.
Ethyl glucuronide (EtG) is the result of the body breaking down ethanol. It is what causes intoxication when someone drinks alcohol.
EtG tests most commonly test urine, but also detect ethanol in hair, blood, or nails.
EtG testing is used in a variety of circumstances, including:
- Court-ordered DWI or DUI programs
- Alcohol treatment programs
- Court cases
- Probation programs
- Professional monitoring
- Liver transplants
EtG tests do not measure for current impairment. Instead, the test determines if someone has consumed alcohol in the last two to three days.
How Does an EtG Test Work?
EtG tests are a decent method for monitoring alcohol consumption, but they aren’t perfect.
This is partly due to the timeframe in which a test must be used and the things a person can do to manipulate their test results.
For example, the more water someone consumes during and after drinking alcohol, the faster their body will excrete the alcohol through urine. Essentially, drinking water dilutes the EtG test results.
Tests can detect relatively low levels (100 ng/ml) of EtG in urine. Even light drinking can create a positive EtG result.
The more someone drinks, the more likely it is that an EtG test will show they were drinking. However, tests are likely to show signs of even very light drinking if administered within 12 hours of consuming alcohol.
How Long Can Alcohol be Detected in an EtG Test?
An EtG test is not effective in determining if someone is currently sober.
Instead, it detects EtG in urine for up to 12 to 72 hours after consumption. This makes it different from a breathalyzer that shows more recent alcohol consumption.
Is an EtG Test Accurate?
EtG tests are considered fairly accurate. But there are several things unrelated to alcohol consumption that can affect the results of the test.
A variety of substances can contaminate the test results, including:
- Breath spray
- Cleaning products
- Hair dye
- Hand sanitizer
- Foods containing alcohol flavoring
- Antiperspirant and other hygiene products
It’s also possible to dilute EtG test results by drinking a lot of water. The more someone urinates after drinking, the faster they’ll excrete EtG from their bodies.
According to SAMHSA, EtG tests have high accuracy rates.1
What are the Limitations of an EtG Test?
The primary limitation of the EtG test is that it can only detect alcohol in someone’s system for about 72 to 80 hours after they’ve consumed it.
Testing must occur at least twice a week if someone must be constantly monitored for alcohol use.
Additionally, false positive and false negative results are possible. Someone can also affect their results by consuming a significant amount of water before taking the test.
How to Interpret EtG Test Results
EtG tests are easy to interpret.
A positive result means there is alcohol in the urine of the test subject. More than likely, alcoholic beverages were consumed within the last two to three days.
A negative result indicates someone has not recently consumed alcohol.
Additionally, results can be divided into high and low positive results.
High positive results could indicate:
- Heavy drinking on the same day or previously (ie, previous day or 2).
- Light drinking the same day
Low positive results could indicate:
- Previous heavy drinking (previous 1-3 days)
- Recent light drinking (past 24 hours)
- Recent intense "extraneous" exposure (within 24 hours or less)
Very low positive results could indicate:
- Previous heavy drinking (1-3 days)
- Previous light drinking (12-36 hours)
- Recent "extraneous" exposure
How to Prepare for an EtG Test
The best way to prepare for an EtG test if you need to achieve a negative result is to not drink for several days before the test. Even a single drink can cause a positive result on an EtG test.
Keep in mind: several things can affect the results of an EtG test.
It’s possible to get both false negative and false positive results depending on the amount of water someone drinks and what substances they’re exposed to before the test.
How Long Before an EtG Test Should You Stop Drinking?
To get a negative result on an EtG test, do not drink any alcoholic beverage at least three days before taking the test. The more you drink, the sooner you should stop drinking before a test.
For example, someone who typically has a drink or two will usually test negative within 48 hours. Heavier drinkers who consume three or more alcoholic beverages in one instance will need to stop drinking at least 72 hours in advance of an EtG test.
If you struggle with substance use, a positive EtG test could indicate a need for professional support.
Alcohol abstinence is about more than just avoiding a positive test. It could reduce your risk of alcohol-related health issues and allow you to better manage your alcohol use.