If you’ve received a positive alcohol test result that you believe is wrong, you have options to challenge it. The process depends on the type of test (breath, urine, or transdermal monitor) and the context (traffic stop, workplace screening, or court-ordered monitoring). A successful dispute typically combines identifying the specific cause of the false reading, gathering supporting evidence quickly, and following the correct procedural channels.
Why False Positives Happen
Alcohol tests measure either ethanol directly or its metabolic byproducts, and several things besides drinking can trigger a positive result. Understanding the likely cause of your false reading is the first step in building a case against it.
Breathalyzers detect alcohol vapor in your exhaled air. Products that contain alcohol or produce alcohol-like compounds can inflate readings significantly. Mouthwash is the most common culprit: Listerine can push a breath reading to 240 mg/dL (three times the legal limit) if used immediately before testing, and Scope can reach 170 mg/dL. These readings drop rapidly and fall well below impairment levels within about 10 minutes, but if a test is administered in that window, the result can look like heavy intoxication. Breath sprays, alcohol-containing cough drops, and over-the-counter cold medicines like NyQuil pose the same risk. Asthma inhalers containing albuterol, salmeterol, or budesonide have also been linked to false positives on breath tests.
Fermented foods, including kimchi, sauerkraut, soy sauce, and yeast-heavy baked goods, can produce trace amounts of alcohol that register on sensitive equipment. Oral pain relievers like Anbesol contain anesthetics that may interfere with breathalyzer readings as well.
For urine-based EtG tests, the picture is different. EtG (a metabolite your liver produces when it processes ethanol) can be detected for up to five days after drinking, depending on the cutoff level used and how much was consumed. But your body also encounters ethanol from non-beverage sources. Hand sanitizers, mouthwashes, and certain cleaning products contain enough alcohol to produce detectable EtG in urine without any drinking at all. This is why SAMHSA recommended in 2012 that labs use a conservative cutoff of 500 ng/mL to reduce false positives from incidental exposure. Many labs and treatment programs still use lower cutoffs of 100 or 200 ng/mL, where false positive rates are higher: at 100 ng/mL, one study found a 6.3% false positive rate over a five-day assessment period, compared to just 1.1% at the 500 ng/mL cutoff.
Transdermal alcohol monitors (like SCRAM bracelets) measure alcohol vapor through your skin. Lotions, hand sanitizers, and cleaning supplies that contact the bracelet area can trigger false readings. Device malfunctions also occur.
Medical Conditions That Produce Alcohol
Some people’s bodies produce ethanol internally. Auto-brewery syndrome (also called gut fermentation syndrome) is a condition where fungi or bacteria in the digestive system convert carbohydrates into ethanol. People with this condition can register blood alcohol levels consistent with intoxication, sometimes extremely high, without consuming a single drink. In one documented case, a patient’s blood alcohol concentration exceeded 400 mg/dL, a level that would typically cause unconsciousness.
Auto-brewery syndrome is more common in people with short bowel syndrome, small intestinal bacterial overgrowth (SIBO), or intestinal motility disorders. People with both type 2 diabetes and liver cirrhosis have also shown elevated internal ethanol production, with blood alcohol levels reaching over 22 mg/dL from carbohydrate intake alone. If you suspect this condition, a gastroenterologist can perform a carbohydrate challenge test, where you eat a controlled amount of carbohydrates and your blood alcohol is monitored over several hours. A confirmed diagnosis is powerful evidence in a dispute.
Steps to Dispute a Breathalyzer Result
Standard protocol requires a 15 to 20 minute observation period before administering a breath test, during which the officer watches to confirm you haven’t eaten, vomited, or put anything in your mouth. If this observation period was skipped or cut short, the result is vulnerable to challenge. Mouthwash used minutes before a stop could have produced the reading, and without the waiting period, there’s no way to rule that out.
Request an independent blood test as soon as possible. Blood tests measure actual blood alcohol concentration directly and are far less susceptible to the mouth-alcohol contamination that plagues breath tests. In most states, you have the legal right to request an independent test after a breathalyzer. The sooner this happens, the more useful the comparison between results. A breath test showing 0.10 followed by a blood test 30 minutes later showing 0.00 is strong evidence of a false positive.
Document everything you consumed or used in the hours before the test: medications (prescription and over-the-counter), food, mouthwash, breath spray, cough drops, inhalers. Receipts, medication bottles, and even timestamped photos can support your account. If you were using an asthma inhaler or had taken NyQuil, your attorney can argue these substances produced the reading.
Check whether the breathalyzer device was properly calibrated and maintained. Breathalyzers require regular calibration, and law enforcement agencies maintain logs of when each device was last serviced. Your attorney can subpoena these records. A device that was overdue for calibration or had a history of inconsistent readings weakens the prosecution’s case significantly.
Challenging an EtG Urine Test
EtG tests are particularly prone to disputes because of the incidental exposure problem. If your test came back positive at a cutoff below 500 ng/mL, the result may reflect hand sanitizer use, mouthwash, or other non-beverage alcohol sources rather than drinking. Knowing the exact cutoff level used and your result in ng/mL is essential information for your dispute.
Start by documenting your exposure to alcohol-containing products. Many workplaces have hand sanitizer dispensers. Many hygiene routines include mouthwash. If you work in a setting where you regularly contact alcohol-based cleaners or sanitizers, this context matters. Request a retest using a higher cutoff or a different testing method. A confirmatory test using a different analytical technique can help distinguish true drinking from environmental exposure.
If your positive EtG result is being used in a treatment program, probation, or custody case, ask what cutoff level was applied. Programs using the 100 ng/mL cutoff are casting a very wide net. At that threshold, nearly 1 in 15 results may be a false positive. The 500 ng/mL cutoff recommended by SAMHSA specifically exists to avoid punishing people for incidental exposure, and you can cite this federal guidance in your appeal.
Disputing a SCRAM Bracelet Reading
SCRAM monitors are designed to distinguish between consumed alcohol and environmental alcohol by analyzing the pattern of the reading. A drinking event produces a characteristic rise-peak-fall curve over several hours, while a splash of hand sanitizer on the bracelet area typically produces a sharp spike that drops off quickly. However, the technology isn’t perfect, and false positives from environmental exposure remain a recognized issue.
If you get a flagged reading, document what products you were using and what you were doing at the time. Cleaning with alcohol-based products, applying certain lotions near the bracelet, or working in environments with airborne alcohol (like a bakery or auto detailing shop) can all produce readings. Your monitoring company will review the data pattern before reporting a violation to the court, but you should proactively provide your explanation and any supporting evidence.
What to Do in a Workplace or DOT Test
Department of Transportation alcohol testing follows a two-step process. A screening test (breath or saliva) is administered first. If it reads 0.02 or above, a confirmation test using an evidential breath testing device is required. Only a confirmed result of 0.04 or higher is reported as a violation. If your screening test was positive but no confirmation test was performed, the result should not be treated as a violation.
For non-DOT workplace tests, your employer’s policy dictates the process, but most reputable testing programs include a confirmation step and the option to have your sample retested at a different lab. Ask your HR department or the testing facility for the specific chain-of-custody documentation and confirmation results. If only a screening test was performed, push for confirmatory testing.
In any workplace dispute, request a copy of the full test report, including the type of test used, the cutoff level, whether a confirmation test was run, and the chain-of-custody log showing your sample was properly handled. Errors in sample handling, unlabeled specimens, or missing documentation can invalidate a result regardless of what it showed.
Building the Strongest Case
Time is your biggest constraint. If you believe a breath test was wrong, request an independent blood test immediately. If a urine test was wrong, request a retest as soon as possible, ideally from a split sample if one was collected. The longer you wait, the harder it becomes to produce contradicting evidence.
Keep a written log of everything you consumed, applied to your body, or were exposed to in the 24 hours before the test. Include medications with dosages, hygiene products by brand name, foods, and any workplace chemical exposures. This log should be created as soon as possible while your memory is fresh.
If a medical condition like auto-brewery syndrome could explain your result, get tested by a specialist and obtain written documentation. If medications are the likely cause, get a letter from your prescribing doctor confirming what you take and that it can affect alcohol testing. In legal cases, expert witnesses, typically toxicologists or forensic chemists, can testify about the limitations of the specific test used and the plausibility of a false positive given your circumstances. In employment or probation contexts, a well-documented explanation supported by medical records often carries enough weight to resolve the dispute without formal litigation.