Legally Reviewed By:
Brian P. Gabriel, Esquire
Many people assume that failing a field sobriety test or breathalyzer automatically means someone was driving under the influence, but this isn’t always the case. Certain medical conditions can produce symptoms or test results that mimic intoxication, potentially leading to wrongful DUI charges.
Criminal Defense Attorney Brian Gabriel has experience defending clients against DUI charges where medical conditions, not alcohol, may have contributed to symptoms or test results. With knowledge of how these conditions affect breathalyzer testing, effective strategies can be employed to challenge breathalyzer evidence.
How Breathalyzers Work and Their Limitations
Breathalyzer technology, while widely used by law enforcement across the country, operates on scientific principles that can be influenced by various factors beyond alcohol consumption. These devices use chemical reactions or infrared spectroscopy to detect compounds in breath samples, but they cannot always distinguish between ethanol and other similar molecular structures that may naturally occur in the body.
Most breathalyzer tests work by detecting compounds with a methyl group structure, which includes ethanol (drinking alcohol) but also encompasses many other substances that can appear in human breath naturally or due to medical conditions.
Medical Conditions That Can Affect Breathalyzer Results
Several legitimate medical conditions can cause false positives on breathalyzer tests or produce physical symptoms that resemble intoxication, creating situations where innocent drivers may face unwarranted DUI charges.
Diabetes and Ketosis
Diabetes can produce false-positive breathalyzer readings through a process called ketosis. When diabetics have low insulin levels or haven’t eaten for a while, their bodies break down fat for energy, creating ketones. One such ketone, acetone, can be converted in the body to isopropyl alcohol.
Certain breathalyzers cannot distinguish between isopropyl alcohol and ethanol (drinking alcohol), potentially resulting in falsely elevated BAC readings. Additionally, during a hypoglycemic episode, a diabetic person may display symptoms like confusion, slurred speech, and poor coordination, all of which officers might mistake for intoxication.
Auto-Brewery Syndrome
Auto-brewery syndrome, also known as gut fermentation syndrome, is a rare but scientifically documented medical condition that can create alcohol in the body without consuming alcoholic beverages. This condition occurs due to an overgrowth of certain yeasts or bacteria in the digestive system that ferment carbohydrates into ethanol.
The symptoms include many typical signs of intoxication, such as disorientation, slurred speech, and impaired coordination, making it nearly indistinguishable from actual alcohol consumption to an observing officer.
GERD, Acid Reflux, and Heartburn
Gastroesophageal reflux disease (GERD), acid reflux, and related digestive conditions can significantly impact the accuracy of breathalyzer tests through a mechanism involving the regurgitation of stomach contents. These conditions affect the sphincter separating the stomach from the esophagus, potentially allowing alcohol to move upward from the stomach.
Most breathalyzers are designed to measure deep lung (alveolar) air, but when mouth alcohol is present due to GERD or related conditions, the device may detect this residual alcohol instead, potentially pushing readings above legal limits even when blood alcohol is within legal ranges.
Respiratory Conditions
Respiratory disorders such as asthma, COPD (chronic obstructive pulmonary disease), and bronchitis can interfere with breathalyzer accuracy and produce symptoms that law enforcement might misinterpret as signs of impairment. These conditions fundamentally affect breathing patterns and lung function, which are critical to proper breathalyzer operation.
These conditions may prevent the person from providing a sufficient breath sample, which some officers might interpret as a refusal to comply, or may alter the ratio of alcohol in breath compared to blood due to breathing difficulties or medications that could interfere with breathalyzer chemistry.
Florida’s Ongoing Transition to a New Breath Test Device
Florida is in the process of phasing out the long-used Intoxilyzer 8000 in favor of the newer Intoxilyzer 9000, with new operational procedures taking effect statewide in 2026. During this transition period, which device was used in your specific case, and whether it was properly calibrated and operated under the correct procedures for that device, is an additional factor an attorney should review alongside any medical conditions that could explain your results.
Why Legal Representation Matters
Securing competent legal representation is crucial if you face DUI charges and believe a medical condition may have influenced your breathalyzer results or physical symptoms. An attorney with experience in DUI cases and knowledge of how medical conditions affect testing can make a meaningful difference in how your case is defended.
If you’re arrested for DUI and have a medical condition that could have affected your test results, proper legal representation is essential. An experienced attorney will identify relevant medical conditions that may have influenced your breathalyzer results, help you obtain medical documentation and expert testimony to support your defense, and review the validity of the testing procedures used in your case.
Contact an Experienced Defense Attorney
Being charged with DUI due to breathalyzer results that may have been affected by a medical condition can be frightening and frustrating. With proper legal representation and medical documentation, you may have options to challenge these charges. Mr. Gabriel will handle your case using the knowledge and skill developed over the span of his career.
Start with a free consultation today. You can also complete an online contact form to learn more.
Frequently Asked Questions About Medical Conditions and DUI Testing
Can diabetes really cause a false positive on a breathalyzer test?
Yes. Ketosis related to diabetes can produce acetone that some breathalyzers cannot distinguish from ethanol, potentially resulting in a falsely elevated reading. Medical documentation of your condition can support this explanation in a defense.
What is auto-brewery syndrome and how common is it?
Auto-brewery syndrome is a rare, medically documented condition where an overgrowth of yeast or bacteria in the digestive system ferments carbohydrates into ethanol inside the body. While uncommon, it is a recognized diagnosis that can explain intoxication-like symptoms without alcohol consumption.
Does GERD or acid reflux really affect breathalyzer accuracy?
It can. Breathalyzers are designed to measure deep lung air, but if stomach contents containing alcohol move up into the mouth due to reflux, the device may pick up that residual mouth alcohol and produce an inflated reading.
Which breath test device was used matters, why?
Florida is transitioning from the Intoxilyzer 8000 to the newer Intoxilyzer 9000, with new procedures taking effect in 2026. Confirming which device was used and whether it was properly calibrated and operated is a separate line of defense alongside any medical explanation for your results.
What documentation should I gather if I believe a medical condition affected my test?
Medical records diagnosing the condition, notes from your treating physician, and any relevant test results are helpful. Your attorney can help identify what documentation will be most useful for your specific situation.
Brian Gabriel is the driving force behind the Law Office of Gabriel & Gabriel. He has been in practice for over 30 years and his experience during that time has been devoted almost exclusively to the defense of criminal cases.
August 12, 2026
