Can Mouthwash Throw Off a Breath Test?

After a person is pulled over on suspicion of driving under the influence (DUI), generally the police officer will ask the driver to perform the field sobriety tests. Since these tests are hard for even sober drivers to pass, people typically fail them.

Usually, the officer asks the driver to take a breath test after they failed the field sobriety tests. However, if there’s any suspicion of DUI, the officer will ask for a breath test even if the driver says, “No” to the field sobriety tests.

A person can refuse a breath test to avoid implicating themselves for DUI, but their refusal will result in a one-year suspension of their California driver license under the “Implied Consent Law.” However, should a driver take a breath test, a skilled DUI defense attorney can work to show that the breath test may be flawed.


One thing that can throw off a breath test is the presence of mouth alcohol. A breathalyzer device assumes the breath exhaled into the machine comes from the lungs. While a breathalyzer can determine the level of alcohol in the bloodstream by reading the amount in the lungs, there is no way of determining that the alcohol the machine is reading actually originated from the lungs instead of the mouth.

We bring this up because a lot of people keep a bottle of mouthwash in their vehicles. Not because they’re trying to cover up alcohol on their breath, but because they don’t always have access to a toothbrush in between meals. Some drivers keep a small bottle inside the driver’s side door or in the center console or glove compartment and they’ll use it throughout the day.

The question we get all the time is, “Can the alcohol in my mouthwash throw off a breath test?” In a word, yes. If there is any alcohol in a person's mouth or throat, the breath machine will read this as coming from a person's lungs.

If a driver has used mouthwash before the breath test, there is a chance that the breathalyzer reading might be thrown off. When a person burps, any alcohol that may be in their body can be pushed into their mouth and esophagus, throwing off a reading. Therefore, there are a number of factors that can cause a breath reading to be much higher than a driver's BAC truly is.

Related: Should I Refuse a Breath Test in a CA DUI?

What a Board-Certified DUI Expert Says

According to our Board-Certified DUI Defense Attorney, Virginia L. Landry, "Mouthwash, as well as other items ingested or rinsed, can falsely elevate a breath alcohol reading. Many people will brush their teeth or use mouthwash rinses before leaving a club and starting their drive home.”

“If used right before driving, a common belief is that an officer will not be able to ‘smell’ alcohol. Forensic studies generally agree that after a deprivation period of 15 minutes (California Department of Health Services Regulations, Title 17, section 1219.3), any mouth alcohol (such as mouthwash) will have dissipated. That may be true under a controlled study environment, but there are many ‘interfering substances’ which can falsely elevate a reading; mouthwash is just one of them,” says Attorney Landry.

To challenge your breath test results in an Orange County DUI case, contact the Law Offices of Virginia L. Landry, Inc. today.

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