Are Ignition Interlock Devices Accurate?

Are Ignition Interlock Devices AccurateParticipating in Maryland’s Ignition Interlock Program can be stressful. Advertisements for ignition interlock devices out that their accuracy is “unparalleled,” but this isn’t always the case. These devices are meant to prevent drunk driving, but several things can cause false positive readings that lead to problems with your ability to drive.


An ignition interlock is a device installed on a vehicle that prevents a driver from starting the car if the device detects alcohol on the driver’s breath. It is basically a breathalyzer test connected to a car’s ignition. Unlike breathalyzers, however, the ignition interlock device is not being used to detect whether the user is over the legal limit for intoxication. The device will not allow you to start the car if it detects even a small amount of alcohol on the user’s breath.


There are some things you do every day that can lead to a false positive result on an ignition interlock device:

  • Mouthwash–Rinsing your mouth out with mouthwash right before you head out the door can lead to a false positive reading. Mouthwash contains a relatively high amount of alcohol, and you do not have to swallow the mouthwash for it to test positive. Ignition interlock companies recommend that you rinse your mouth with water for several seconds after using mouthwash and that you wait a few minutes before attempting to use the device.
  • Spicy Foods–when you eat spicy foods it can react with chemicals in your stomach and produce methane gas. The presence of methane can register as a false positive on the device. Using antacids before blowing in the device might help alleviate this problem.
  • Certain Diets or Being Diabetic–people with diabetes and people on certain diets may have high levels of acetone in their body. This acetone can be misread as alcohol and lead to a false positive.
  • Yeast and Sugar–these are two ingredients that can be used to produce alcohol. Rinsing your mouth with water after eating things like donuts and cinnamon rolls can help prevent a false positive.


If you’ve been arrested for DUI, you need an experienced criminal attorney on your side. Contact the attorneys at Alpert Schreyer, LLC or call us at (301) 494-9620 to schedule a free consultation.

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