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Can a Breathalyzer be Wrong?

man taking a breathalyzer test

Whenever you get behind the wheel of a car, you give “implied consent” to submit to a breathalyzer. Blow a high number, and you face charges. Refuse, and you might face other penalties. But what happens if a medical condition gives the breathalyzer a false reading? Can a breathalyzer be wrong?


A strict ketogenic diet is one of the top causes of false breathalyzer readings. As your body enters ketosis, it produces ketones. One of the more prevalent ketones is acetone.

Acetone’s molecular structure is indistinguishable from ethanol, the molecule that gets you drunk. Because the two structures are so similar, portable breathalyzers cannot distinguish between the two. As a result, a sober person on the keto diet can blow as high as 0.06%!


When you have low blood sugar (sugar is a carb), the body creates ketones to compensate. Your body will naturally produce acetone, albeit far less than in the case of a strict keto diet.

While a diabetic person will blow a lower number, the symptoms of low blood sugar are shockingly similar to being drunk. A person with low blood sugar may shake, feel fatigued, become flushed, struggle to walk, and feel stomach sickness. Without specialized training, a police officer can easily mistake those symptoms for intoxication, especially when paired with an elevated BAC.

Fair Warning

If you have these medical conditions, you should still submit to a breathalyzer test, but inform law enforcement about your condition before you blow. If you have diabetes, you might even inform them you have insulin.

If they take you to the station, the wall-mounted breathalyzer should clear up any misunderstandings. The more sensitive instruments are better able to distinguish between your body’s natural acetone and the ethanol in alcoholic drinks.

If you were charged with a DUI, you might want to legal representation. If you’d like an experienced New Jersey DUI attorney from Law Offices of Joseph R. Donahue, LLC to evaluate your case, please send us an email or call (201) 574-7919.

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