Someone in a monitoring program uses hand sanitizer a dozen times during a shift, gargles with mouthwash before a meeting, or drinks a bottle of kombucha at lunch. Days later an EtG test comes back positive, and they have not had a drink. This is not a hypothetical. It is a documented, repeatable finding in the toxicology literature, and it is the reason most alcohol monitoring programs no longer rely on EtG alone.
What EtG and EtS actually measure
Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are minor metabolites formed when the body processes ethanol, the alcohol found in beverages, hand sanitizer, mouthwash, and a surprising number of food and personal care products. Unlike a breathalyzer, which measures active alcohol in the blood over a matter of hours, EtG and EtS can be detected in urine for up to roughly 80 hours after exposure, which is why they are used for abstinence monitoring in treatment programs, probation, family court, and some workplace return-to-duty agreements. The tradeoff for that long detection window is sensitivity to alcohol exposures that have nothing to do with drinking.
SAMHSA's 2012 revision of its clinical advisory on alcohol biomarkers lays this out directly: EtG and EtS are useful, but they are not specific to beverage alcohol, and a positive result requires interpretation, not automatic assumption of consumption. The advisory specifically names hand sanitizer, mouthwash, vanilla extract, cough syrup, and certain fermented foods as sources of incidental exposure that can produce a positive EtG result in someone who has been fully abstinent. It also cautions that biomarkers should never stand in for a full clinical picture, patient interview, and corroborating information, and should not be the sole basis for a punitive decision (SAMHSA Advisory, The Role of Biomarkers in the Treatment of Alcohol Use Disorders).
Hand sanitizer: inhalation, not skin absorption, is the real driver
The strongest and most cited research on this specific scenario comes from a controlled study that separated two possible exposure routes: ethanol absorbed through the skin during hand disinfection, and ethanol vapor inhaled while the product evaporated. The finding was clear. Skin absorption alone did not produce meaningful EtG levels, but inhaling the vapor from repeated hand sanitizer use did. Test subjects who disinfected their hands multiple times in a poorly ventilated space produced EtG concentrations as high as 2.1 mg/L, well above common cutoffs, and levels stayed elevated for hours after the last application. When researchers added simple exhaust ventilation to clear the vapor, EtG excretion dropped to mostly undetectable (Inhalation but not transdermal resorption of hand sanitizer ethanol causes positive ethyl glucuronide findings in urine).
A separate complication involves the type of sanitizer. Some hand sanitizers use isopropyl or n-propyl alcohol instead of, or alongside, ethanol. One study documented false-positive results on an EtG immunoassay screen, up to 4 mg/L, caused by propyl alcohol metabolites cross-reacting with the test rather than true ethanol exposure. The false positives resolved once the samples were confirmed with mass spectrometry, which does not confuse propyl glucuronide for ethyl glucuronide (False-positive ethyl glucuronide immunoassay screening caused by a propyl alcohol-based hand sanitizer). The practical lesson is the same either way: frequent hand sanitizer use in an enclosed space is a real, reproducible way to trigger a positive screen without a drop of beverage alcohol.
Mouthwash, kombucha, and vanilla extract
Mouthwash gets blamed constantly and deserves a fair look. A controlled study had participants gargle with high-ethanol-content mouthwash four times a day for over three days, an intensity well beyond normal use. Out of dozens of specimens collected, only one showed a detectable EtG result, and it was a modest 173 ng/mL, well under the 500 ng/mL cutoff most programs use. That means casual, occasional mouthwash use is unlikely to cause a problem on its own, but sustained heavy use, especially close to a scheduled test, can push a result into positive territory at lower cutoffs (Ethyl glucuronide, ethyl sulfate, and ethanol in urine after intensive exposure to high ethanol content mouthwash).
Kombucha is a different story, and one that surprises a lot of people who consider it a health drink rather than an alcohol source. Kombucha continues to ferment after bottling, and even products labeled non-alcoholic can carry a small residual ethanol content. In a 2022 study, drinking regular kombucha produced detectable EtG and EtS in urine in the majority of participants within the first few voids after consumption, with EtG levels averaging in the hundreds of ng/mL. Hard kombucha, which is intentionally alcoholic, produced far higher and longer-lasting levels, with some individual EtG results well above 10,000 ng/mL. Both markers cleared within about a day in most cases, but that window is enough to catch someone on a same-day or next-day test (Evaluation of Alcohol Markers in Urine and Oral Fluid After Regular and Hard Kombucha Consumption).
Vanilla extract is the classic textbook example because it is roughly 35 percent alcohol by volume, close to the strength of a distilled spirit, and it is used undiluted in baking. SAMHSA's own biomarker advisory lists it by name alongside mouthwash and cough syrup as a documented source of incidental EtG and EtS exposure. A home baker who tastes batter repeatedly, or someone who works in a bakery kitchen, is not a hypothetical case as far as the research is concerned.
Cutoff selection: why 100 ng/mL and 500 ng/mL give very different pictures
The single biggest lever a program has for managing this problem is the cutoff it chooses. A lower cutoff catches more true drinking events but also catches more incidental exposure. A higher cutoff misses light or very recent drinking but is far less likely to flag someone who used sanitizer or ate baked goods.
| Cutoff | What it is designed to catch | Incidental exposure risk | Typical use case |
|---|---|---|---|
| 100 ng/mL | Very low-level or recent drinking, high sensitivity | Meaningful risk from sanitizer, mouthwash, kombucha, or fermented foods | Strict abstinence programs (some treatment courts, MAT programs) that accept the tradeoff for maximum sensitivity |
| 500 ng/mL | Moderate to heavy drinking, or repeated light drinking over 1 to 2 days | Low; incidental exposure studies generally stay below this level under normal use | SAMHSA's recommended default for forensic and workplace-adjacent monitoring where false positives carry serious consequences |
SAMHSA's advisory recommends 500 ng/mL as the more defensible line for programs where a positive result triggers serious consequences, precisely because the incidental exposure literature clusters below that number under normal, non-excessive product use. Programs that need maximum sensitivity, such as some intensive treatment settings, may still choose 100 ng/mL, but they need a plan for interpreting borderline results rather than treating every positive as an admission of drinking.
Why programs pair EtG with EtS instead of running EtG alone
EtG has one well-known vulnerability that has nothing to do with incidental exposure: bacterial contamination. If a urine specimen sits at room temperature or gets contaminated with certain bacteria, particularly in a person with a urinary tract infection, the sugar in urine can ferment into a small amount of ethanol, which the body never processed at all, or bacterial enzymes can degrade EtG after collection and produce a false negative in someone who did drink. EtS is chemically different and is not subject to either of those failure modes in the same way. Running both markers together, and confirming any immunoassay screen with mass spectrometry rather than relying on the screen alone, is the standard way labs and monitoring programs separate a genuine drinking event from a lab artifact or an incidental exposure. This is also why a specimen that screens positive on an immunoassay needs a confirmation step before anyone acts on it, the same logic used for lab confirmation of any non-negative drug screen.
Practical guidance for people in a monitoring program
If abstinence is being verified with EtG, a few habits reduce the odds of an avoidable dispute. Use foam or gel hand sanitizer in a ventilated space rather than repeatedly dosing hands in a closed car or small office, since inhalation, not skin contact, is what drives the positive result. Rinse with water after mouthwash rather than swallowing residue, and avoid gargling repeatedly right before a scheduled test. Treat kombucha, including bottles labeled non-alcoholic, as a real alcohol source and avoid it for at least a day before testing if the program has a low cutoff. Read labels on cough syrups and other liquid medications, since many still use ethanol as a solvent. None of this is a guarantee, because biology varies by body size, metabolism, hydration, and product concentration, but it addresses the exposure routes the research has actually confirmed. For programs and employers building out a broader alcohol testing protocol, comparing EtG against other options such as PEth testing or point-of-collection alcohol test strips is worth doing before locking in a single method.
What this means for programs setting policy
None of this research argues that EtG is unreliable as a monitoring tool. It argues that a positive result at a low cutoff, standing alone, is not proof of drinking, and that a defensible program treats it that way. That means selecting a cutoff appropriate to the stakes involved, pairing EtG with EtS rather than running EtG in isolation, confirming any positive screen before treating it as final, and giving the tested individual a real chance to explain and document incidental exposure before consequences are applied. Employers building or buying an alcohol testing program can review cutoff-appropriate options through workplace drug and alcohol testing solutions designed around these same interpretation principles.
Frequently asked questions
Can hand sanitizer alone cause a positive EtG test?
Yes, under the right conditions. Research shows that inhaling hand sanitizer vapor during repeated use in a poorly ventilated space produces measurable EtG in urine, sometimes above common cutoffs, even when none of the product is swallowed. Skin absorption by itself is not the main driver; it is the vapor being breathed in that matters most.
Does mouthwash realistically cause a false positive in normal use?
Normal, occasional mouthwash use rarely pushes EtG above a 500 ng/mL cutoff. A controlled study using intensive, repeated high-alcohol mouthwash exposure over several days produced only one detectable result, and it was well below that threshold. Heavy or unusually frequent use close to a test time is where risk rises.
Is kombucha actually a risk for someone on EtG monitoring?
Yes. Even kombucha marketed as non-alcoholic can carry residual ethanol from ongoing fermentation, and a controlled study found detectable EtG and EtS in most participants after drinking regular kombucha, with much higher levels after hard kombucha. Anyone on a low-cutoff monitoring program should treat kombucha as an alcohol-containing beverage.
Why do programs test for both EtG and EtS instead of just EtG?
EtS is not affected by the bacterial contamination and fermentation issues that can create false positives or false negatives with EtG alone. Testing both markers together, and confirming any immunoassay screen with mass spectrometry, gives a much more reliable picture of whether beverage alcohol was actually consumed.
What cutoff should a workplace or monitoring program use?
SAMHSA's advisory recommends 500 ng/mL as the more defensible default where a positive result triggers serious consequences, since incidental exposure from products like sanitizer, mouthwash, and food generally stays below that level under normal use. A 100 ng/mL cutoff is more sensitive to actual drinking but also more sensitive to incidental exposure, so programs that use it need a clear process for reviewing borderline results.
Related reading
This article is general information, not medical or legal advice. Anyone facing consequences from an alcohol biomarker test should consult the program's written policy and, where appropriate, a qualified medical review officer or attorney before assuming a result reflects actual drinking.
