What does “false positive” mean for EtG?
The phrase can describe several different situations: analytical error, genuine ethanol exposure from a non-beverage source, ethanol formation in a sample, or a result that is technically positive but misinterpreted. These are not identical problems.
Common incidental exposure sources
- Alcohol-based hand sanitizer used heavily or in enclosed spaces
- Mouthwash and breath sprays containing ethanol
- Some liquid medications, foods, flavorings, and hygiene products
- Workplace exposure to ethanol-containing products
Sample storage and fermentation
Under some conditions, microorganisms and available glucose can complicate urine alcohol testing. Proper collection, storage, and confirmatory analysis reduce avoidable uncertainty. EtG and EtS patterns may provide additional context.
What to do with an unexpected result
Ask for the numerical concentration, cutoff, confirmation method, creatinine or sample-validity information, collection time, and whether EtS was measured. Discuss the result with the responsible clinician, laboratory, attorney, or program rather than relying on an online calculator.
Evidence and limitations
This guide summarizes primary research and public-health guidance. Group-level findings cannot predict one person's result.