How long does an EtG test detect alcohol?

What EtG actually measures

When you drink, your body breaks down almost all of the alcohol quickly. A small fraction is converted into two byproducts, ethyl glucuronide (EtG) and ethyl sulfate (EtS). These byproducts stay in urine much longer than alcohol itself does. That is why an EtG test answers a different question than a breath test. A breathalyzer tells you whether alcohol is in the body right now. An EtG test tells you whether someone has likely been drinking over the past few days.

SAMHSA guidance on clinical testing notes that breath and blood alcohol are detectable for hours, not days, after the last drink (SAMHSA TAP 32). EtG fills that gap.

The short answer: typical detection windows

• Up to about 5 days at a 500 ng/mL screening cutoff, according to Mayo Clinic Laboratories.
• Lower cutoffs look further back. In a study of adults in addiction treatment, researchers found that cutoffs between 100 and 200 ng/mL caught more drinking over 1 to 5 days than the common 500 ng/mL cutoff, which missed more drinking (Lowe et al., 2015).
• Heavier drinking stays visible longer than a single drink, because there is more EtG to clear.
• It is not a stopwatch. No test can tell you the exact hour someone last drank.

You may also hear EtG described as an “80 hour” or “72 hour” test. Those numbers are shorthand for a common range, not a guarantee. The honest answer is that the window runs from roughly one day to several days depending on the factors below.

Why cutoffs matter so much

A cutoff is the concentration a test treats as positive. Results below the cutoff are reported as negative, even if some EtG is present. A lower cutoff catches more drinking and catches it for longer. A higher cutoff reduces the chance of flagging incidental exposure, such as heavy use of alcohol based hand sanitizer.

The Lowe study looked at how well different cutoffs matched what patients reported drinking. It identified optimal cutoffs that fell as time passed: about 420 ng/mL for drinking in the prior 24 hours, about 150 ng/mL at 48 hours, and about 100 ng/mL at 72 hours. The authors recommended 200 ng/mL as a practical cutoff for detecting drinking beyond 24 hours (Lowe et al., 2015). Mayo’s confirmation testing by LC-MS/MS uses separate cutoffs for EtG (250 ng/mL) and EtS (100 ng/mL) (Mayo Clinic Laboratories).

What this means for you: when someone tells you how long EtG “lasts,” ask which cutoff they mean. Two programs can get different answers from the same sample.

Factors that change the window

How much and how often

One glass of wine produces far less EtG than a night of heavy drinking. Repeated heavy drinking over several days can extend detection further.

Timing of the test

EtG appears in urine within hours of drinking and peaks later. A test taken very soon after a single drink may look different than one taken the next morning.

Hydration

Drinking a lot of water before a test dilutes urine and lowers concentrations. Labs check for dilution, and a dilute result is usually treated as a reason to retest rather than a clean result. See our guide on dilute urine results.

Body and health differences

Kidney function, body size and metabolism vary. That is one reason labs and clinicians avoid predicting a precise window for any individual.

How EtG results should be used

A SAMHSA advisory on alcohol biomarkers, summarized by RTI, emphasizes that biomarkers like EtG work best alongside conversation and screening, not as the only piece of evidence (SAMHSA advisory summary). Mayo likewise advises that EtG and EtS results be interpreted in the context of all available clinical and behavioral information (Mayo Clinic Laboratories).

In practice, a good monitoring program uses EtG as one tool among several:

• Random timing, so a person cannot simply plan around the window.
• Pairing EtG with breath tests when you want to know about drinking right now as well as over recent days.
• Asking about products that contain alcohol before the test. Our guide on EtG and incidental alcohol exposure covers this in detail.
• Talking through any positive result with a real person before anyone draws conclusions.

If you are trying to stay sober and worried about a test

If you drank and you are anxious about an upcoming test, the most useful thing you can do is be honest early. A result is information, not a verdict. Many people who return to drinking need more support, not more punishment. NIAAA’s Rethinking Drinking site is a good, private place to look at your own drinking and options for cutting back or stopping.

If you are struggling right now, call or text 988 to reach the Suicide and Crisis Lifeline. In an emergency, call 911.

How Blackburn Monitoring can help

Blackburn Monitoring offers EtG alcohol testing alongside breathalyzer and 12 panel urine drug testing in Los Angeles, at a low cost. A monitoring coordinator sets a schedule case by case, sends you an electronic notice when it is time to test, and shares results quickly with only the people you authorize in writing. Testing is by appointment at our office at 12326 Venice Blvd, Monday to Friday, 9 AM to 5 PM, with other Westside locations for off hours and mobile testing at home or work for an additional fee.

Learn more about our EtG alcohol test, how it compares with a breathalyzer, or how an ongoing monitoring program works. If drinking has become hard to manage, our team can introduce you to therapy and psychiatric care at Blackburn Clinical Services.