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You may have found our website while Googling interlock devices, which means that you need information on the subject because you, or someone you know, has recently been caught drinking and driving.

Everyone makes mistakes, and it just so happens that alcohol-impaired driving incidents are common on our roads. Ignition interlock devices are a great way to return normalcy to your life during your probationary period.

That said, you likely have questions about this device.

Over the years, many people have asked us if the interlock device can fail for something as harmless as a mouthwash. This is a great question that deserves an answer.

What Does an Interlock Device Do?

An interlock device is a breathalyzer that measures the level of alcohol on your breath before it will allow the car to start. You may have to breathe into the device several times while driving, depending on how far you’re going.

Previous generations of interlocks were slow to start, sensitive to temperature, and couldn’t differentiate between human residual mouth alcohol and breath alcohol concentration (BrAC). The new models make all the difference when it comes to mouthwash.

RoadGuard Interlock devices are discreet, more resilient in all temperatures, and are the most sensitive in detecting the difference between mouth and lung alcohol content. This doesn’t mean, however, that a DUI isn’t a serious issue.


Can Mouthwash Cause a Failed Interlock?

Most mouthwashes contain a significant percentage of alcohol. Listerine, for example, has an alcohol content of 26.9%, while whisky has around 40%. Even the most sensitive of breathalyzers can register erroneous results regarding such a large percentage of alcohol.

Mouthwash isn’t the only thing that can cause you to fail the interlock device.

Below are some reasons for it:

  • Being on a restrictive diet or having diabetes
  • Eating spicy foods
  • Using throat spray or Chloroacetic
  • Eating baked goods, such as cinnamon rolls

The whole point of having the interlock device is to continue living your life as seamlessly as possible. But how can you live your best life without essential items like cold medication?

What Do I Do?

You don’t have to change the way you eat or give up your oral hygiene habits for the interlock device. Yes, mouthwash may cause you to fail a breathalyzer test. It’s rare, but it can happen. However, you can take certain precautions to avoid any unnecessary lockouts that can ruin your day.

First, don’t drink alcohol. Many people have discovered over the years that a night of drinking can lead to miserable mornings when their car refuses to start.

Secondly, if you’ve eaten recently, drink some water to cleanse your pallet 15 minutes or so before you try to start the car. Go by the same rules for mouthwash, cold medicine, and those delicious cinnamon rolls.

If you wake up late, don’t just gargle mouthwash instead of brushing your teeth. Rinse your mouth with water or grab an apple. Eating an apple will get that morning film off your teeth and nourish your body. Best of all, it won’t lock your interlock device and prevent your car from starting.

Get a RoadGuard Interlock Device for Continuity and Security

If you fail the interlock breath test, your car won’t be able to start. Your best bet is to obtain a quality device for your money because every failed test is recorded. If you have too many of them, your right to drive can be rescinded.

So, play it safe and go with a RoadGuard Interlock device. Our interlock devices are small and discreet. They are also more sensitive to the differences between mouth and lung alcohol content than other brands.

Contact us at RoadGuard Interlock if you have questions regarding ignition interlock devices or need to schedule an appointment. We can even install one on your motorcycle! Let’s get you back on the road quickly and safely.


*Links to any third-party websites herein are provided for your reference and convenience only. RoadGuard Interlock did not create nor develop and does not own any such third-party websites. RoadGuard Interlock does not endorse nor support the content of, nor any opinions stated in any such third-party website links. RoadGuard Interlock is not responsible for the content of any third-party website or its accuracy or reliability. Nothing contained in this article or in any such third-party website shall be considered legal advice or be deemed to constitute legal advice. For any legal advice concerning a DUI arrest, charge, conviction, or consequences thereof, you should contact an attorney of your choice. *