What Is an EtG Urine Test and How Accurate Is It?

An EtG urine test detects ethyl glucuronide, a metabolite your body produces only when it processes alcohol. Because EtG can linger in urine for roughly two to five days after drinking, the test is far more sensitive than a standard alcohol breath or blood test, which clears within hours. That sensitivity cuts both ways, though. The test is remarkably good at catching recent drinking, but it can also flag people who never intentionally consumed alcohol, and its accuracy shifts depending on the cutoff threshold a lab uses, how the sample is handled, and even individual biology.

How EtG Gets Into Your Urine

Most of the alcohol you drink is broken down through the familiar route: your liver converts ethanol to acetaldehyde and then to acetic acid, which your body eventually burns for energy. But a small fraction takes a different path. Liver enzymes attach a sugar molecule (glucuronic acid) to ethanol, creating ethyl glucuronide.¹ This reaction is a standard detox process your liver runs on all sorts of foreign substances. The resulting EtG molecule is water-soluble and gets filtered out through your kidneys into your urine, where it sticks around well after the alcohol itself is gone.² A companion metabolite called ethyl sulfate (EtS) is produced through a parallel pathway and is usually measured alongside EtG.

The amount of EtG your body produces is dose-dependent: the more you drink, the more EtG shows up in your urine.³ That relationship is why labs and monitoring programs use different concentration thresholds to distinguish light drinking from heavy drinking, or recent exposure from something days ago.

What the Cutoff Numbers Mean

When a lab reports an EtG result, it compares the concentration in your sample against a predetermined cutoff. The most commonly used cutoffs are 100, 200, and 500 nanograms per milliliter (ng/mL), and which one is chosen has a dramatic effect on what the test catches and what it misses.

A study of addiction treatment patients found that the 100 ng/mL cutoff had the highest sensitivity across time periods, catching about 93% of drinking episodes at 24 hours and still catching roughly 78% at five days out. The tradeoff was lower specificity, meaning more false positives. Bumping the cutoff to 200 ng/mL dropped sensitivity somewhat but improved specificity considerably. Cutoffs at 300 ng/mL and above caught fewer drinkers but produced very few false alarms, with specificity reaching into the high 90s.⁴

In practice, this means a 500 ng/mL cutoff is often interpreted as a strong signal of recent, heavier drinking. One study found that threshold caught about 78% of heavy drinking episodes within one day but less than 71% over the next two to five days, and it identified only about 68% of light drinking on day one.⁵ A lower cutoff like 100 or 200 ng/mL picks up more drinking events, including lighter ones, but opens the door to results triggered by non-beverage sources of alcohol. The 500 ng/mL threshold is the one the Substance Abuse and Mental Health Services Administration (SAMHSA) has historically recommended for clinical use, precisely because it reduces the chance of calling someone positive who merely used hand sanitizer or mouthwash.

Things That Can Trigger a Positive Without Drinking

This is the part of EtG testing that generates the most anxiety and controversy. Because the test is sensitive to tiny amounts of ethanol from any source, products you would never think of as “alcohol” can produce measurable EtG in your urine.

Hand Sanitizer

Alcohol-based hand sanitizers contain 60% or more ethanol. Some of that ethanol gets absorbed through your skin, but the bigger route of exposure is inhalation of the vapor. In one study, volunteers who used an ethanol-based hand sanitizer every five minutes for ten hours over three consecutive days produced urine EtG concentrations as high as 2,001 ng/mL, well above even the 500 ng/mL cutoff.⁶ That is an extreme scenario (healthcare workers who sanitize dozens of times a shift are the closest real-world parallel), but even more moderate exposure can cause detectable levels. A separate study found that multiple rounds of hand disinfection caused positive EtG findings in four out of five test subjects, and two people who merely stood nearby and breathed the vapor also tested positive.⁷ When ventilation was used to remove the vapor, EtG levels dropped to near zero, confirming that inhalation was the main absorption route.

Some hand sanitizers use propyl alcohol instead of ethanol. These can still cause false positives on EtG immunoassay screening tests because the antibodies used in the screening cross-react with propyl glucuronides. In one experiment, normal use of a propyl alcohol sanitizer produced immunoassay results as high as 4 mg/L (4,000 ng/mL).⁸ A confirmatory test using a more precise method would catch this kind of error, which is one reason many labs run a second analysis on positive screening results.

Mouthwash

Many popular mouthwashes contain between 10% and 27% alcohol. Gargling with a 12%-ethanol mouthwash produced EtG levels above 100 ng/mL in roughly a third of urine samples collected over 24 hours, and a few exceeded 200 ng/mL. When volunteers gargled three times daily for five days, some morning urine samples still showed EtG above 50 ng/mL, though all stayed under 120 ng/mL.⁹ Another investigation found the highest concentration from mouthwash use was 366 ng/mL EtG after an excessive number of rinses over eight hours.¹⁰ At a 500 ng/mL cutoff, normal mouthwash use is unlikely to cause a positive, but at 100 or 200 ng/mL it absolutely can.

Non-Alcoholic Beer

Beverages labeled “non-alcoholic” can contain up to 0.5% alcohol by volume, depending on the jurisdiction. Drinking several in a sitting is enough to produce measurable EtG. One study found urine EtG concentrations as high as 0.87 mg/L (870 ng/mL) after non-alcoholic beer consumption, and in one volunteer whose urine concentrated overnight, levels reached 14.1 mg/L (14,100 ng/mL) by morning.¹¹ If you are being monitored for abstinence, non-alcoholic beer is not a safe choice, regardless of what the label says.

How Bacteria Can Distort Results in Both Directions

An underappreciated problem with EtG testing is what happens to the sample between the moment it leaves your body and the moment a lab analyzes it. If urine is contaminated with certain bacteria, two opposite things can happen. First, bacteria like E. coli can break down EtG that is already present, potentially turning a legitimate positive into a false negative. EtS is resistant to this breakdown, which is one reason labs often measure both markers together.¹² Second, the same bacteria can produce EtG from scratch if there is any free ethanol in the sample, either from contamination or from the bacteria’s own fermentation of glucose in the urine. One study found that E. coli-infected urine samples generated EtG concentrations ranging from 0.5 to 17.6 mg/L after storage, levels that would easily exceed any clinical cutoff.¹³

Proper preservation matters. Adding certain preservatives like boric acid or chlorhexidine to urine collection tubes prevents bacterial degradation of EtG during storage and transport.¹⁴ Labs that handle EtG testing routinely use preserved tubes, but if you are being tested at a facility that is not accustomed to this particular assay, poor sample handling could skew the result. A discordant result where EtG is negative but EtS is positive, or vice versa, is a red flag that something went wrong with the sample rather than a clean answer about whether drinking occurred.¹⁵

Why the Same Amount of Alcohol Can Give Very Different Results

People sometimes assume that EtG levels translate neatly to how much someone drank, but the relationship is far from one-to-one. The enzymes responsible for creating EtG vary in activity from person to person, and research has documented as much as an eightfold difference in peak blood EtG concentrations among individuals given the same dose of alcohol.¹⁶ Those differences likely stem from genetic variations in the liver enzymes that produce EtG, as well as interactions with other drugs that compete for the same enzymes.

Hydration also plays a role. A dilute urine sample can push EtG below the cutoff even after genuine drinking, while concentrated urine (from dehydration or the antidiuretic effect alcohol itself has on the body) can amplify the reading. In one analysis, urine creatinine was significantly higher in EtG-positive samples compared to negatives, consistent with alcohol’s late antidiuretic effect concentrating the urine.¹⁷ This means two people who drank the same amount at the same time could produce very different EtG readings depending on their genetics, hydration, kidney function, and what medications they take. Treating EtG as a breathalyzer-style quantitative measure of how much someone drank is a mistake.

Immunoassay Screening Versus Confirmatory Testing

Most initial EtG tests are run using an immunoassay, which is fast and relatively cheap. The immunoassay uses antibodies that bind to EtG, and the signal is interpreted as positive or negative against the chosen cutoff. The limitation is that immunoassay antibodies are not perfectly selective. They can cross-react with structurally similar molecules, including glucuronides from non-ethanol alcohols like the propyl alcohol in some hand sanitizers.

Confirmatory testing uses liquid chromatography-tandem mass spectrometry (LC-MS/MS), a method that identifies molecules by their exact chemical fingerprint rather than by antibody binding. Both major commercial immunoassay platforms compare well to LC-MS/MS for samples that are truly positive above 500 ng/mL.¹⁸ Below that threshold, discrepancies increase. If your livelihood or legal standing depends on the result, asking whether a confirmatory LC-MS/MS analysis was performed is worth the effort. Many monitoring programs require it automatically for positive screens, but not all do.

How EtG Compares to Other Alcohol Biomarkers

EtG is not the only way to test for alcohol use, and depending on the situation, it may not be the best one. The main alternatives are phosphatidylethanol (PEth), measured in blood, and carbohydrate-deficient transferrin (CDT), also measured in blood.

PEth has a much longer detection window than EtG. It reflects drinking over the previous two to four weeks rather than just the past few days. In head-to-head comparisons, PEth consistently outperforms EtG in sensitivity. A study of healthcare professionals in monitoring programs found that PEth identified alcohol use more often than EtG at every cutoff tested.¹⁹ In a large transplant population, PEth correctly identified drinking in about 89% of cases where alcohol had been consumed, compared to roughly 40% for EtG/EtS.²⁰ The same study estimated that switching to PEth-only testing could save institutions over $720,000 in testing charges while catching more drinking episodes.

CDT, on the other hand, is far less sensitive than either PEth or EtG. It mainly picks up sustained heavy drinking over weeks and misses lighter or more episodic use.²¹ CDT remains part of some European driver’s license reinstatement protocols, but research suggests it misses a substantial share of cases that PEth or EtG would catch.²²

EtG’s practical advantage is convenience: it only requires a urine sample, and urine is easy to collect, transport, and test. PEth requires a blood draw, which creates more logistical friction for programs doing frequent random testing. Many monitoring programs use EtG as a frequent screening tool and add PEth when they need a longer look-back window or when EtG results are ambiguous.

Where EtG Testing Shows Up in Practice

EtG testing is widespread in settings where abstinence from alcohol is either legally mandated or clinically important. Courts order it in DUI probation, child custody disputes, and drug court programs. Professional licensing boards for physicians, nurses, pilots, and attorneys use it to monitor practitioners in recovery. Substance abuse treatment programs use it to verify self-reported abstinence during outpatient care.

In transplant medicine, EtG testing plays a particularly high-stakes role. Patients with alcohol-related liver disease are typically required to demonstrate a period of abstinence before being listed for a transplant, and ongoing monitoring continues afterward because relapse to heavy drinking significantly threatens graft survival.²³ The sensitivity of EtG is valuable here, but so are its limitations. A transplant team needs to distinguish between a patient who had a single slip and one who is drinking heavily again, and EtG levels alone cannot reliably make that distinction because of all the variability discussed earlier.

EtG testing has also been explored in prenatal and neonatal screening. Researchers have detected EtG in meconium (a newborn’s first stool), where it serves as a record of alcohol exposure during the later months of pregnancy. In one study, EtG was present in all meconium samples tested, including from mothers whose interviews and medical records showed no reported alcohol use, raising questions about the sensitivity of clinical questionnaires and the ubiquity of low-level ethanol exposure.²⁴

EtG in Hair

Urine EtG captures drinking in a window of roughly two to five days, but EtG is also deposited in hair as it grows, creating a record that extends back months. Hair EtG testing is used in some European countries as part of driver’s license reinstatement assessments, where authorities need evidence of sustained abstinence rather than a snapshot of the last few days. Research comparing hair EtG to CDT in that context found hair EtG substantially more sensitive at catching excessive and chronic drinking patterns.²²

Hair testing has its own complications. Hair treatments like bleaching and dyeing can reduce EtG levels in the strand, potentially leading to false negatives. Hair growth rate varies between individuals and across different parts of the body. And very low levels of drinking may not deposit enough EtG to be detected in a standard hair sample. Still, for programs that need to look back three to six months rather than three to five days, hair EtG fills a gap that urine testing cannot.

What to Do if You Are Being Tested

If you are in a monitoring program that uses EtG testing, a few practical points are worth keeping in mind. Avoid alcohol-containing mouthwash and switch to an alcohol-free brand. Be aware that heavy use of ethanol-based hand sanitizer, especially in poorly ventilated spaces, can produce a positive. Non-alcoholic beer is not reliably alcohol-free and can generate EtG levels above common cutoffs. Some medications and food products (certain vanilla extracts, fermented foods, kombucha) contain trace alcohol and could theoretically contribute, though the research on those sources is thinner.

If you receive a positive result you believe is wrong, ask whether the test was confirmed by LC-MS/MS. Ask what cutoff was applied. A result of 150 ng/mL at a 100 ng/mL cutoff means something very different from a result of 5,000 ng/mL. And if EtS was tested alongside EtG, a discordant result (one positive and the other negative) suggests a sample handling problem or an immunoassay cross-reaction rather than genuine alcohol consumption. Positivity rates for EtG are generally higher in clinical settings than in forensic ones, partly because clinical samples may involve patients with urinary tract infections or other factors that complicate interpretation.²⁵