Yes, ETG false positives can happen—but they're less common than many people fear.
If you're worried about an ETG false positive from hand sanitizer, mouthwash, or other products, this guide explains the real risks based on scientific research. We'll cover the most common causes and give you practical steps to protect yourself.
- Hand sanitizer CAN cause positives—but mainly through inhalation in enclosed spaces, not normal hand use.
- Alcohol-containing mouthwash poses a real risk, especially at the 100 ng/mL cutoff.
- True false positives are relatively rare at the 500 ng/mL cutoff.
- If you believe you got a false positive, you can request EtS confirmation testing.
Can Hand Sanitizer Cause a False Positive?
This is the question everyone asks. Let's look at what the research actually says.
The Science
A key study (PubMed 24631832) found that inhalation—not skin contact—is the main risk. Healthcare workers using alcohol-based hand sanitizers in poorly ventilated areas showed elevated ETG levels.
Normal handwashing? The alcohol evaporates before significant absorption can occur through skin.
Risk by Cutoff Level
| Cutoff | Hand Sanitizer Risk | Notes |
|---|---|---|
| 500 ng/mL | Very low | Normal use unlikely to cause positives |
| 100 ng/mL | Moderate | Heavy/frequent use in enclosed spaces may elevate levels |
| 50 ng/mL | High | Rare/strict cutoff—avoid alcohol-based products entirely |
Who Should Be Careful
- Healthcare workers using sanitizer dozens of times daily
- Anyone working in enclosed, poorly ventilated spaces with frequent sanitizer use
- People facing 100 ng/mL or lower cutoffs
What You Can Do
- Use in well-ventilated areas when possible
- Consider alcohol-free alternatives before testing (look for benzalkonium chloride instead)
- Don't panic about occasional normal use—research shows this is low risk
Ingredient Checklist
Before your test, check product labels for these ingredients:
❌ Avoid (contain ethanol):
- Denatured Alcohol
- Ethanol / Ethyl Alcohol
- SD Alcohol
- Isopropyl Alcohol (less concerning but still avoid if possible)
✅ Safe alternatives:
- Benzalkonium Chloride (common in alcohol-free sanitizers)
- Cetyl Alcohol (not a drinking alcohol—safe for skin products)
- Cetearyl Alcohol (fatty alcohol—no ETG risk)
Mouthwash and ETG Tests
Alcohol-containing mouthwash is a more legitimate concern than hand sanitizer.
The Risk
Products like Listerine contain 21-27% alcohol. When you swish and spit, some alcohol is absorbed through your mouth lining. Studies (PubMed 17137525) show this can elevate ETG levels.
How Big Is the Risk?
| Cutoff | Risk Level | Recommendation |
|---|---|---|
| 500 ng/mL | Low for normal use | Single use typically fine |
| 100 ng/mL | Moderate | Switch to alcohol-free 48+ hours before test |
Safe Alternatives
Look for "alcohol-free" on the label:
- Crest Pro-Health
- Biotene
- TheraBreath
- ACT Anticavity (alcohol-free versions)
Other Potential False Positive Sources
Fermented Foods
Foods with trace alcohol include:
- Kombucha — Can contain 0.5-3% alcohol
- Overripe fruit — Natural fermentation occurs
- Vinegar-based sauces — Trace amounts
- Bread — Yeast produces small amounts during rising
Risk level: Very low at 500 ng/mL. At 100 ng/mL, consuming large amounts of kombucha could theoretically elevate levels.
Medications
Some liquid medications contain alcohol as a solvent:
- Certain cough syrups (NyQuil, some prescription medications)
- Some liquid antibiotics
- Certain herbal tinctures
What to do: Check labels. Tell your testing provider about any medications you're taking.
Cooking with Alcohol
Wine in pasta sauce? Beer in chili?
The good news: Cooking evaporates most alcohol. The remaining amount is typically too small to cause positive results at standard cutoffs.
Cleaning Products
Using alcohol-based cleaning products in enclosed spaces could theoretically cause inhalation exposure—similar to hand sanitizer. Normal household cleaning with ventilation is not a significant risk.
The Science: Why False Positives Happen
Understanding the mechanism helps you assess your real risk.
How ETG Forms
When you consume alcohol, your liver converts it to ETG (ethyl glucuronide). This happens regardless of how the alcohol enters your body:
- Ingestion — Drinking alcohol (primary source)
- Inhalation — Breathing alcohol vapors (can cause positive results)
- Transdermal — Skin absorption (minimal for most products)
Why Cutoffs Matter
Lower cutoffs catch smaller amounts of ETG. A 100 ng/mL test is 5x more sensitive than a 500 ng/mL test.
This means:
- Incidental exposure that's invisible at 500 ng/mL might show at 100 ng/mL
- The same hand sanitizer use could be "safe" for one test but not another
What Research Says
The SAMHSA advisory on ETG testing specifically notes that the 500 ng/mL cutoff was chosen to minimize false positives from incidental exposure while still detecting actual drinking. Lower cutoffs increase sensitivity but also increase incidental exposure risk.
How to Prevent False Positives
Follow these steps 48-72 hours before your test:
Products to Switch
| Product Type | Avoid | Use Instead |
|---|---|---|
| Hand sanitizer | Alcohol-based | Benzalkonium chloride products |
| Mouthwash | Listerine, Scope | Crest Pro-Health, Biotene |
| Hair products | Alcohol-containing gels | Alcohol-free alternatives |
| Hand wipes | Alcohol wipes | Soap and water |
Foods to Limit
- Skip kombucha entirely
- Avoid overripe fruit
- Check sauces for wine/beer content
Medications to Check
- Review all liquid medications for alcohol content
- Notify your testing provider about any you can't avoid
Environment
- Use hand sanitizer in well-ventilated areas
- Avoid enclosed spaces with heavy sanitizer use
What to Do If You Believe You Got a False Positive
Getting an unexpected positive result is stressful. Here's how to handle it:
Step 1: Stay Calm
Don't immediately argue or become defensive. Take time to think through your exposure history.
Step 2: Document Everything
Write down:
- All products you've used in the past 72 hours
- Any medications taken
- Your work environment (healthcare, cleaning, etc.)
- Foods consumed
Step 3: Request Confirmation Testing
You have options:
- LC-MS/MS confirmation — More accurate than initial screening
- EtS (ethyl sulfate) testing — EtS is more specific to alcohol ingestion and less affected by incidental exposure
If your ETG is positive but EtS is negative, this supports an incidental exposure explanation.
Step 4: Know Your Rights
- In legal/probation settings, you may have the right to challenge results
- Consult with a lawyer if the result has significant consequences
- Keep all documentation of potential exposure sources
Related Resources
- ETG Calculator — Estimate your current level
- ETG Test Cutoff Levels — Understand different thresholds
- Factors Affecting ETG — What influences your results
- Realistic ETG Detection Times — Expected detection windows
Scientific References
The information on this page is based on peer-reviewed research:
- Reisfield GM, et al. (2011). "Ethyl glucuronide, ethyl sulfate, and ethanol in urine after sustained exposure to an ethanol-based hand sanitizer." Journal of Analytical Toxicology, 35(2):85-91. (PMC4832416)
- Arndt T, et al. (2014). "Inhalation but not transdermal resorption of hand sanitizer ethanol causes positive ethyl glucuronide findings in urine." Forensic Science International, 237:126-130. (PubMed 24631832)
- Costantino A, et al. (2006). "The effect of the use of mouthwash on ethylglucuronide concentrations in urine." Journal of Analytical Toxicology, 30(9):659-662. (PubMed 17137525)
- SAMHSA Advisory (2012). "The Role of Biomarkers in the Treatment of Alcohol Use Disorders."
Research shows that inhaling alcohol from hand sanitizer (common in enclosed spaces) can cause positive EtG results. However, normal handwashing without inhalation is unlikely to cause false positives at 500 ng/mL. Healthcare workers using sanitizer frequently in poorly ventilated areas face higher risk.
Alcohol-containing mouthwash (like Listerine) can cause elevated EtG levels, especially at the stricter 100 ng/mL cutoff. At 500 ng/mL, normal use is unlikely to cause positives. If you're being tested, switch to alcohol-free mouthwash at least 48 hours beforehand.
True false positives (from incidental exposure) are relatively rare at the 500 ng/mL cutoff. They become more common at 100 ng/mL. Most 'false positives' are actually true positives from forgotten or underestimated alcohol consumption, not from products.
You can request confirmation testing using LC-MS/MS and EtS (ethyl sulfate). EtS is more specific to alcohol ingestion and less affected by incidental exposure. Document any potential exposure sources and consult with a lawyer if the result has legal consequences.
Foods with trace alcohol include overripe fruit, kombucha, bread, vinegar-based sauces, and dishes cooked with wine/beer. However, these rarely cause positives at 500 ng/mL. At 100 ng/mL, consuming large amounts of fermented foods might theoretically elevate levels.
48-72 hours before testing: Use alcohol-free hand sanitizer and mouthwash, avoid kombucha and overripe fruit, check medication labels for alcohol content, and avoid alcohol-based cleaning products in enclosed spaces.
This page is for educational purposes only. It does not constitute medical or legal advice. If you receive an unexpected positive result, consult with your testing provider, healthcare professional, or legal counsel for guidance specific to your situation.