Can Having Asthma Adversely Affect BAC Readings?

 Posted on May 29, 2025 in DUI

If you are facing an Illinois DUI, it is crucial that all your defense options be considered. For some people, an illness or disease – or the medications used for that illness or disease – can cause a spike in blood alcohol levels that has little to do with actual inebriation. While it might seem like a long shot to blame a high BAC reading on something other than alcohol consumption, it can be a valid defense.

Both the disease of asthma itself, as well as the medications used to treat asthma, can have an adverse effect on a breathalyzer test, causing higher readings. If you are facing DUI charges, discussing these issues with your Joliet, IL DUI lawyer is important. Your attorney could potentially have your DUI charges dropped or have the charges lowered to one with less serious consequences.

How Could Asthma Distort the Final Breathalyzer Measurement?

The breathalyzer machine takes a sample of air at the end of the subject’s exhalation into the device, measuring the results of the final amount of air released. This makes the ultimate result of the breathalyzer test dependent on the final part of an exhalation rather than the average alcohol concentration of the entire breath. The breathalyzer works this way because the air that is deeper in the lungs is more concentrated.

Smaller lungs must exhale a larger amount of air in relation to their size (breathe out for a longer period of time) to fulfill the breath test. In short, smaller lungs lead to a higher BAC result. While asthma does not specifically affect the size of an individual’s lungs, it does affect the ability to breathe out.  An individual with asthma must force himself or herself to exhale a considerably larger amount of lung air volume to prevent a falsely high BAC reading. For some, this is simply not possible.  

Asthma Medications That Can Affect BAC Readings

Certain drugs used to treat asthma can also adversely affect breathalyzer readings. Additionally, the propellants used in inhalers could also raise a BAC reading. The asthma drugs that could falsely increase a BAC reading include Salbutamol, Albuterol, Salmeterol, and Budesonide. These asthma drugs leave a residual alcohol-like compound in the mouth, which can mistakenly be read by a breathalyzer as alcohol.  

It is worth noting that the effect these drugs have on a breathalyzer test lasts between 20 minutes and an hour. Because of this, an attorney will have to show that the defendant used his or her inhaler within that window of time prior to taking the breathalyzer test. For example, the stress and anxiety of being pulled over could have caused the defendant to use his or her inhaler before taking the breathalyzer test.

Other Illnesses and Conditions That Could Result in a Falsely High BAC Reading

Those who suffer from acid reflux, chronic heartburn, or gastroesophageal reflux disease (GERD) can experience stomach acid regurgitation into the throat and mouth, which can carry recent alcohol consumption or residual alcohol from foods or medications into the mouth, causing a falsely high BAC reading.

Those with diabetes, especially those who experience hypoglycemia, sometimes have increased amounts of acetone, which is produced when fats rather than carbohydrates are broken down in the body. These acetone levels can then be measured as ethanol, which is what breathalyzers measure.

Even an individual’s diet can cause falsely high BAC readings. When Keto dieters enter a state of ketosis, the body is burning fat rather than carbs, producing ketones that can mistakenly be read as alcohol by a breathalyzer test.   

Contact a Will County, IL DUI Lawyer

If you have been charged with an Illinois DUI, your first step should be to speak to a knowledgeable Joliet, IL DUI attorney from McNamara Phelan McSteen, LLC. We are a mid-sized, aggressive law firm with extensive, specific experience across various legal fields. To schedule a free consultation, call 815-727-0100.