Can Mouthwash Cause a Failed Interlock?

Ignition interlock devices are highly sensitive to alcohol. That’s why all states have ignition interlock laws as part of their effort to prevent DUI offenders from driving drunk again. It’s also why Mothers Against Drunk Driving supports the widespread use of interlocks. Ignition interlock devices (IIDs) are meant to prevent you from starting the car if you have a .02-.025 breath alcohol content (BAC). That’s not very much. So if you’re wondering “can mouthwash cause a failed interlock?” The short answer is yes.

But there is a caveat. Unlike beer, wine, or liquor, the concentrated form of alcohol in mouthwash doesn’t linger. Unless you actually drink it. So if you just swish with mouthwash, and wait 20 minutes before blowing into your interlock, you should pass the test. That is, as long as you haven’t been drinking in the last 12-24 hours.

Mouthwash has more alcohol in it than you might expect. For example:

  • Original formula Listerine has 26.9% alcohol
  • Listerine mint flavors are almost 22% alcohol
  • Scope is 18.9% alcohol
  • Cepacol is 14% alcohol

Compare those alcohol contents to beer (3-7% alcohol) and wine (12%). Some mouthwashes even rival the percentage of alcohol in liquor. So you can see how swishing with alcohol and going right out to start the car could be problematic.

If you like to use mouthwash after brushing your teeth to get that minty fresh feeling, stick with the alcohol-free brands. At least while you have your ignition interlock installed. That way, you don’t have to think twice about it.

If You Think You Failed the Interlock Test Accidentally

If you fail the ignition interlock test after using mouthwash, you should contact your monitoring agency and your service center about what happened and when. Then, rinse your mouth out with water, wait for 10-15 minutes, and submit another breath test. This time, you should be able to start your car.

And be advised, mouthwash isn’t the only everyday item to have a high alcohol content. This is why we suggest you wait 10-15 minutes after eating or drinking before submitting a breath sample. You may also want to swish your mouth out with water first.

Some other items that contain alcohol include:

  • Some breath freshener sprays
  • Some cough syrup
  • Some cold and allergy medications
  • Vanilla extract
  • Certain energy drinks
  • Non-alcoholic beer
  • Vinegar
  • And more

When you have an ignition interlock device installed, it’s a good idea to avoid these items, and pay attention to the ingredients of food and drinks you buy. If you avoid these items during the time you have the ignition interlock device installed, you shouldn’t have a problem.

Our ignition interlock devices are highly accurate, and meet or exceed the National Highway Transportation Safety Administration (NHTSA) model specifications for ignition interlock devices. The ALCOLOCK IIDs have a range of alcohol measurement from 0.000 to 0.500 g/DL and provide results with an accuracy of plus or minus 0.005 at 0.020 g/DL. In other words, they are incredibly accurate, no matter what the source of the alcohol is.

Schedule Your Ignition Interlock Device Installation

If you need to get an ignition interlock device installed, ALCOLOCK is ready to help. Simply call the service location most convenient to you. You can also call ALCOLOCK at (866) 700-9300. When deciding on a service center, remember that where you have your installation done is where you will have your monthly service appointments. So look at the location hours and decide if closer to home or closer to work is a better option. Please have your court or administrative paperwork with you when you call, as we will need some of that information.

In most situations, we can get you an installation appointment within a couple of days of your call. Keep in mind you will need someone to drive you and your vehicle to the service center. You should plan on the appointment to last about an hour. During that time the technician will physically install the device, and train you in how to use it. They will also go over what all of the lights,  sounds, and screen messages mean.

If someone other than you will be driving the car while you have the device installed, they should come to the installation appointment as well. The device needs to be calibrated for all drivers.

Our goal is to make it so when you drive away from your appointment, you are confident in how to use the device, and know exactly what is expected.

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