What is an ETG alcohol test and how does it work?

An EtG alcohol test detects ethyl glucuronide (EtG), a direct metabolite of alcohol, to identify recent alcohol exposure after alcohol itself is no longer measurable. It is used to extend the detection window beyond standard breath or blood tests.

When alcohol is consumed, the body metabolizes most of it into carbon dioxide and water, but a small portion is converted into EtG. This metabolite is excreted in urine and can remain detectable after blood alcohol levels have returned to zero. As a result, EtG testing can identify alcohol use that occurred hours to several days earlier, depending on the amount consumed and individual metabolism.

EtG tests are most commonly performed on urine samples. Laboratories use specific cutoff thresholds to distinguish incidental exposure from drinking. Lower cutoffs increase sensitivity but also raise the chance of detecting trace exposure, while higher cutoffs reduce sensitivity but focus on heavier or more recent use. Because EtG is highly sensitive, products containing alcohol—such as certain mouthwashes or hand sanitizers—can sometimes contribute to low-level positives.

EtG testing does not measure intoxication or impairment. It indicates exposure, not how much alcohol was consumed or when impairment occurred. Timing and quantity cannot be determined precisely from a single result.

Understanding how EtG testing works helps clarify its role. It is designed to monitor recent alcohol use over an extended window, not to assess current impairment or provide exact timelines of drinking.