Posted by duijim in on September 22, 2026
A breath test result can seem like the final nail in the coffin of a DUI case. The machine prints a number, the number is over the limit, and the case seems decided. But it has a major downside drivers rarely hear about: mouth alcohol. Residual alcohol in the mouth or throat can inflate a reading enough to turn a legal result into an arrest.
What Is Mouth Alcohol?
Breath test machines are designed to measure deep-lung air, where alcohol in the bloodstream exchanges with air in the lungs. The machine converts a sample of that air into an estimated blood-alcohol concentration.
Mouth alcohol is anything that disrupts that design: alcohol in the mouth, throat, or upper airway rather than coming from deep in the lungs. Because it is far more concentrated, even a tiny amount can push the reported number sharply upward, and the machine cannot tell the difference.
How GERD and Acid Reflux Can Contaminate a Breath Sample
Gastroesophageal reflux disease, commonly called GERD or acid reflux, is one of the most significant sources of mouth alcohol contamination. With GERD, stomach contents travel back up the esophagus into the throat and mouth. If there is alcohol in the stomach, reflux carries it upward too.
A single reflux episode or burp before a breath test can coat the mouth and throat with alcohol, often without the driver noticing — and a driver who had dinner, drinks, and silent reflux could produce a breath sample that says little about actual blood alcohol.
Dental Work, Dentures, and Braces Can Trap Alcohol
The mouth itself can hold onto alcohol long after a drink is finished. Dentures, braces, retainers, crowns, bridges, and cavities all create small pockets where alcohol becomes trapped, and that trapped alcohol releases slowly into the breath over time.
Unlike reflux, this kind of contamination is constant rather than episodic, which makes it harder for the machine’s built-in safeguards to catch.
A Recent Drink, Mouthwash, or Breath Spray
Timing matters enormously. Alcohol consumed in the minutes before a traffic stop has not cleared from the mouth, so a driver who finished a drink right before driving can have significant mouth alcohol with no connection to impairment.
Everyday products cause the same problem. Mouthwash and breath sprays often contain high concentrations of alcohol, and using either shortly before a breath test can produce a startlingly high reading in a sober person.
What Breath-Test Machines Are Supposed to Do About It
The Intoxilyzer 9000, Georgia’s breath-test instrument, includes a slope detector that monitors the shape of the breath sample. Mouth alcohol produces a distinctive profile, a sharp spike followed by a rapid drop, and when the detector sees it, the sample is supposed to be flagged as invalid. The instrument also compares replicate samples and flags them when consecutive readings differ by more than 0.020.
Officers are also supposed to observe the driver for a 20-minute deprivation period before the test begins, watching for burping, belching, or vomiting. If regurgitation is suspected, the observation period is supposed to start over.
In practice, these safeguards fail more than they should. Observation gets interrupted, the slope detector misses some contaminated samples, and slow alcohol release from dental work may not produce the sharp spike it looks for.
Why Mouth Alcohol Matters in a Georgia DUI Case
A surprising number of DUI prosecutions rest on a breath result only slightly above the legal limit. When the reading is 0.082, a small amount of mouth alcohol contamination can be the difference between a lawful result and a criminal charge.
An Atlanta DUI Lawyer challenging a breath test will look past the number itself: maintenance and calibration records, the printed breath-test ticket showing the sample profile, booking-room video showing whether the driver burped, and medical or dental records documenting GERD or dental work that explain where the contamination came from.
An Atlanta DUI Attorney who understands breath-test science also knows to examine the Intoxilyzer 9000 data logs for the testing session, which can reveal irregularities that never appear on the printed ticket. These records exist, and they can be obtained, but only if someone knows to ask for them.
What to Do If You Have GERD or Dental Work and Face a DUI Charge
If you live with acid reflux or have significant dental work and you were arrested after a breath test, a few steps matter:
- Tell your attorney about the condition right away, including any diagnosis, prescriptions, or remedies you use.
- Gather medical and dental records that document GERD, reflux, dentures, braces, or other relevant conditions.
- Write down everything you remember about the testing process, including whether you burped, felt reflux, or used mouthwash or breath spray that day.
- Do not assume the breath-test number is unbeatable. A DUI Lawyer Atlanta drivers consult regularly sees cases where the science behind the number did not hold up.
A breath result over the limit can also trigger a license suspension, so it is worth understanding the license suspension appeal process and its deadlines.
The Bottom Line
A breath test is a machine, and machines can be fooled. Mouth alcohol from GERD, dental work, a recent drink, or mouthwash can produce a number that looks like intoxication but is really contamination. The safeguards built into the testing process are real, but they are not foolproof.
If mouth alcohol may have affected your test, talk to a DUI Attorney Atlanta residents trust before assuming the case against you is airtight.