Step-by-step Guide on How to Pass a Saliva Drug Test With Listerine

Daniel Miller
Daniel Miller, Ph.D Pharmacology, Drug Testing Specialist

Last updated on 2022 May 11

You can pass a mouth swab drug test using Listerine. This test is sometimes called a saliva drug test or an oral drug test.

Make sure the Listerine you use doesn’t contain alcohol, as alcohol can cause you to fail. However, you cannot use Listerine strips for this purpose.

In this article, I will provide step-by-step instructions on how to use Listerine to successfully pass an oral drug test and what mistakes to avoid.

I will also explain how you can use water instead of Listerine and still pass the test.

listerine for mouth swab drug test

How to pass a mouth swab drug test with Listerine: Step-by-step instructions

Mouth swab drug tests can detect drug use for up to 72 hours by identifying drug molecules in your saliva.

To pass the test, ensure there are no drug molecules in your mouth, or at least keep their concentration in oral fluids below the detectable level. Here’s what you should do:

Abstain from using toxins as long as possible. Brush your teeth thoroughly. Get a bottle of Listerine that doesn’t contain alcohol.

Using mouthwash with alcohol can make you fail not only the urine drug test but also the mouth swab test for alcohol.

Wash your mouth with Listerine for 30 seconds. Do this at least three times. Doing it just once will only remove part of the drug molecules; you need to repeat it several times to reduce their concentration as much as possible.

After this process, your mouth will be clean from drug metabolites for 2 hours. If you need to pass the drug test after 2 hours, use the method again. That’s all there is to it.

Can I use Listerine strips?

listerine strips

No, you can’t use Listerine strips for this purpose. The main point of using Listerine to pass a mouth swab drug test is to rinse your mouth with a liquid.

You could also use other liquids like hydrogen peroxide, milk, or water. Listerine strips don’t rinse your mouth; they simply dissolve and may increase saliva production.

However, just producing more saliva isn’t enough to remove drug molecules from your mouth cavity. I’ll explain why this is important later.

Now, I’ll explain why this method works and why you can use water instead of Listerine.

How swab drug tests detect marijuana

Saliva drug tests are becoming more popular because they are more accurate than urinalysis. These tests can detect marijuana for up to 72 hours after your last use.

The convenience of saliva tests is also their drawback if you’re concerned about passing one. They can be administered anywhere – by the roadside, at the workplace – often without prior warning.

The test searches for activated THC (delta-9 THC), the psychoactive compound in marijuana that produces the ‘high’ effect, whether inhaled or ingested.

When you use marijuana, millions of these THC molecules linger in your mouth. They primarily stay in the salivary albumin concentration within your oral cavity. It’s this residue that the test detects, which can lead to a positive result.

How long is THC detectable in saliva?

When it comes to swab drug tests, the length of time THC remains detectable in your saliva is crucial. A study published in the Journal of Analytical Toxicology investigated this by monitoring THC levels in the saliva after controlled marijuana smoking.

In the study, six participants smoked cannabis cigarettes with 1.75% THC during the first week and 3.55% THC the following week.

Their saliva was then tested at various times using Gas Chromatography-Mass Spectrometry (GC-MS).

Twelve minutes after beginning to smoke, one sample showed a THC concentration of 5800 ng/ml. By the 20th minute, this had dropped to 81 ng/ml, and 12 hours later, levels were below 1 ng/ml.

This pattern – high initial THC levels followed by a rapid decline – was consistent across all participants. The study suggests THC may be absorbed directly into the bloodstream from the mouth, explaining the quick decrease in saliva THC levels.

From this study, we can conclude that THC can stay in your mouth for up to 12 hours after smoking. The good news is that the concentration decreases over time.

Most laboratories set the detection threshold between 10-25 ng/ml, depending on the test.

While this study indicates THC levels fall below detectable levels within 12 hours, some tests can detect THC up to 48 hours after use.

The duration THC remains detectable can also vary based on several factors, such as the amount of marijuana consumed, how long you have been using it, your age, health condition, and the level of salivary albumin in your mouth.

Albumin, a common protein in both blood and saliva, binds strongly with THC.

Studies show that older adults tend to have higher albumin levels in their saliva, which might mean THC lingers longer in their mouths after smoking.

How Listerine works in a saliva drug test

Many believe that Listerine cleans THC molecules from the mouth just as it eliminates bacteria. Others think that its bacteria-killing properties also destroy THC, making it undetectable in tests.

Some suggest that Listerine’s active ingredients – menthol, thymol, methyl salicylate, and eucalyptol – might interfere with the test’s accuracy, potentially causing a false negative.

I’ve found that Listerine does help in passing a swab drug test. However, studies indicate that water might work just as well, if not better.

A 2014 study assessed the effects of different mouthwashes and water on cannabis oral fluid concentrations. This study involved 11 chronic cannabis smokers over four days. Each day, they smoked their usual amount of cannabis.

Oral fluids were collected 30 minutes before smoking and again at various intervals up to 24 hours after smoking.

The participants rinsed their mouths with water, Kleaner, and whole milk, and the specimens were analyzed for THC concentrations.

Results showed that rinsing with water significantly reduced THC levels compared to Kleaner and milk.

Interestingly, 15 minutes after smoking, THC levels were three times higher than the 25 ng/ml cut-off used by Spanish police, regardless of the mouthwash used.


There’s no doubt that Listerine can help you pass a saliva drug test. But what’s truly remarkable is that using water can also be effective.

This means you don’t necessarily have to spend money on Listerine if you need to pass a saliva test and it’s not available.