Mouth alcohol is residual alcohol that is present after a person consumes certain foods or drinks. It is also present in breath sprays, mints, some types of gum, mouthwashes, and some medications. It is important to remember that interlocks have no ability to distinguish between mouth alcohol and alcohol in a person’s bloodstream. There is no dispute that mouth alcohol can cause false positive ignition interlock readings in the form of initial start failures and failed rolling re-tests. Either of these violations can result in harsh consequences in Massachusetts, where the Registry administers the Ignition Interlock Program with a zero-tolerance approach.

Mouth alcohol can also cause false readings in DUI cases. This is why the state breath testing regulations call for a fifteen-minute observation period prior to the administration of an evidentiary breath test.  Because both breathalyzers and ignition interlocks are designed to measure deep lung air, alcohol blown directly into either type of device can result in very high readings.

In order to avoid month alcohol problems, ignition interlock users should not consume anything by mouth that could trigger a false positive IID reading for 15 minutes prior to attempting to drive. It is safe to drink water and to rinse with water prior to taking an initial start or re-test. In the event of false positive readings, IID users should consider mouth alcohol as a potential cause. Some ignition interlock devices are programmed to delay follow up tests to allow mouth alcohol to subside. Fortunately, mouth alcohol dissipates fairly quickly and waiting a few minutes can allow the alcohol to reach an acceptable level.

There are different types of alcohols and any chemical which ends in “ol” is a member of the alcohol family. This means that a medication such as albuterol, which is commonly used to in inhalers treat asthma, can trigger false readings. Anti-freeze and some windshield washer fluids which contain ethylene glycol to keep the product from freezing can also trigger false interlock results.

Common breath sprays which people use to mask bad breath often contain alcohol and these have been known to generate inaccurate readings. Interlock users should be aware this and stop using them to prevent potential failed breath tests and resulting license revocations.

When reviewing alcohol readings, mouth alcohol can usually be identified because the alcohol level will fall rapidly, due to the rapid dissipation of mouth alcohol as opposed to alcohol in a person’s bloodstream which is measured by an analysis of deep lung air.

Massachusetts Ignition Interlock customers who experience violations due to mouth alcohol should immediately document the circumstances and contact the Registry as well as the IID service provider. It might be possible to get an exculpatory test at a police station or medical facility such as an urgent care clinic, laboratory, or hospital.