False positives on alcohol tests, including breathalyzers and urine screens, can occur for various reasons unrelated to consuming alcoholic beverages. Multiple medications, both prescription and over-the-counter, contain ethanol or compounds that can be mistaken for it during testing. In other cases, underlying medical conditions can alter bodily processes, leading to misleading results. Understanding these factors is essential for anyone facing alcohol testing, whether for legal, employment, or medical reasons.
Why Do Medications Trigger False Positives?
The reasons behind a medication causing a false positive on an alcohol test fall into several categories:
Alcohol-Containing Ingredients
Some medications and oral hygiene products contain ethanol as a preservative, solvent, or active ingredient. Liquid medicines, in particular, often use alcohol to dissolve ingredients or enhance flavor. For instance, certain cough syrups and cold medications like NyQuil or Vicks formulas contain alcohol that can be detected, especially on a breathalyzer, shortly after use. Similarly, mouthwash and breath sprays with high alcohol content can cause temporary spikes in a breathalyzer reading if used just before a test.
Metabolic Interference
Certain drugs can interfere with the body's metabolic processes in a way that produces alcohol-like byproducts. The antibiotic Metronidazole (Flagyl) is known for this. While it doesn't contain alcohol, it can cause an adverse reaction with alcohol and produces metabolites that some tests can misinterpret. Similarly, some medications for diabetes, like sulfonylureas, can create alcohol-like byproducts that may affect urine tests for ethyl glucuronide (EtG) or ethyl sulfate (EtS), which are markers for alcohol use.
Delivery Method
Some asthma inhalers use alcohol as a propellant to help deliver the medication deep into the lungs. When used, this small amount of alcohol is exhaled, and if a breathalyzer test is administered too soon afterward, it can result in a positive reading. While typically a temporary issue, it's a critical detail for individuals with asthma to be aware of.
Sample Contamination and Medical Conditions
Beyond medications, other factors can cause false positives, particularly with urine tests. Improper handling or storage of a urine sample can lead to bacterial fermentation, where bacteria or yeast in the sample convert glucose (sugar) into ethanol. This is especially relevant for diabetic patients whose urine contains high levels of glucose. Additionally, medical conditions like diabetes and acid reflux can produce acetone or other compounds that some older breathalyzer devices may incorrectly identify as alcohol.
Specific Medications and Products That Cause False Positives
Over-the-Counter Products
- Cough Syrups: Many liquid formulations for coughs and colds contain ethanol, such as some versions of NyQuil, Robitussin, and Vicks products.
- Mouthwashes and Breath Sprays: A significant number of these products have high alcohol content and can cause a false breathalyzer reading for a short period after use.
- Oral Gels: Topical gels for toothaches or canker sores, like Anbesol, can have a very high concentration of alcohol and skew breathalyzer results.
- Hand Sanitizers: The alcohol in hand sanitizers can transfer to the mouth through touch or be exhaled, potentially impacting a breathalyzer if used immediately before the test.
Prescription Medications
- Antibiotics: Metronidazole is the most well-documented antibiotic that can cause issues, but certain quinolone antibiotics have also been noted to interfere.
- Asthma Inhalers: Some inhalers containing steroid medications use an alcohol propellant, which can be temporarily detected on a breath test.
- Antidepressants: Certain antidepressants, such as sertraline, have been known to cause false positives for other substances, like benzodiazepines, but can also interfere with EtG testing in rare cases.
- Benzodiazepines: These depressants can cause 'drunk-like' symptoms and interfere with test accuracy.
- Anti-Diabetic Medications: Oral hypoglycemics, particularly some sulfonylureas, may lead to metabolic byproducts that interfere with urine testing.
Comparison of Medications and Test Interference
| Medication/Product Type | Common Examples | Test(s) Affected | Mechanism of Interference | Detection Timeframe |
|---|---|---|---|---|
| OTC Cough Syrups | NyQuil, Robitussin | Breathalyzer, EtG/EtS (urine) | Contains ethanol directly | Short-term for breath, longer for EtG/EtS |
| Mouthwash | Scope, Listerine | Breathalyzer | Contains high concentrations of ethanol | Minutes after use |
| Metronidazole (Flagyl) | Prescription Antibiotic | EtG/EtS (urine) | Metabolic byproducts mimic ethanol markers | Hours to days |
| Asthma Inhalers | Beclomethasone, Albuterol | Breathalyzer | Alcohol propellant in aerosol | Minutes after use |
| Hand Sanitizer | Ethanol-based sanitizers | Breathalyzer | Ingestion or inhalation of ethanol vapor | Minutes after use |
| Oral Gels | Anbesol, Orajel | Breathalyzer | High alcohol content | Minutes after use |
How to Handle Potential False Positives
If you believe a medication has caused a false positive result, taking the following steps is crucial:
- Read Labels Carefully: Always check the ingredients of OTC medications and oral products for alcohol. When possible, opt for alcohol-free versions if you are subject to testing.
- Inform Testing Personnel: Before a test, disclose all prescription medications, over-the-counter drugs, and supplements you have taken. This is critical for legal and employment testing to provide context for any non-negative results.
- Request Confirmatory Testing: If a breathalyzer or initial urine screen shows a positive result, request a more specific and accurate confirmatory test, such as a Gas Chromatography-Mass Spectrometry (GC-MS) test. GC-MS can differentiate between various substances and provide more precise data. For breathalyzers, waiting 15-20 minutes and re-testing can often show a significant drop in a false positive reading caused by residual mouth alcohol.
- Provide Documentation: For employment or legal purposes, gather documentation from your doctor regarding your prescriptions and the timing of your medication use.
Conclusion
In summary, various drugs and common household items can lead to false positive alcohol test results, primarily due to their ethanol content, metabolic interactions, or delivery method. From common cold medications to specific prescription antibiotics, the list of potential culprits is extensive. Individuals subject to regular testing should be aware of these possibilities and take proactive steps, such as checking product labels and informing testing authorities of their medication use. Ultimately, the best course of action is to request a more accurate, lab-based confirmatory test to ensure the validity of the result. For additional information on pharmacological interactions, consider consulting resources like the National Institutes of Health (NIH).
