How to Pass A Mouth Swab Drug Test

how to pass a mouth swab drug test

While cannabis is legal in an increasing number of states, that doesn’t mean employers aren’t still testing for it. If anything, legalization has renewed interest in drug testing (largely to do with the alleged increase in people driving under the influence), particularly mouth swabs. Mouth swabs are some of the most commonly used drug tests, and it benefits everyone to know how to pass one. 

So how do mouth swabs differ from other types of drug testing, and how can you pass one easily? Here, we’ll discuss the science of mouth swabs, what they test for, how long THC stays in your saliva, and how you can accelerate the process of clearing it out to pass a drug screen.

What Do Mouth Swabs Test For?

Saliva tests differ from urine tests in the chemical compound they test for. Urinalysis screens for both THC and its primary metabolite, THC-COOH. Saliva tests, on the other hand, test only for activated THC, or delta-9 THC, the stuff that ends up on the inside of your mouth after taking a bong rip, a puff off a vape, or a bite of an edible. 

In a way, this is good news: it means that, since THC doesn’t stick around long in your saliva, the ability of the test to detect cannabis consumption is pretty short-lived. It also means that the test won’t pick up lingering metabolites in your system. However, it still tests for the psychoactive, and thus illicit, delta-9 THC that lingers in your spit in the period following consumption.

How Long Does THC Stay In My Saliva?

Fortunately for cannabis consumers, THC doesn’t hang out in your saliva for very long, and any THC metabolites on their way out of your system from your salivary glands aren’t going to show up on the test, because the test isn’t looking for them. 

Technically, there’s nothing keeping THC in your saliva. It coats the entire surface of your mouth when you smoke or consume it, but it dissipates pretty quickly after that. Even if you, for instance, literally never brush your teeth (gross), THC would only remain detectable in your saliva for a week or less after you last consumed it. For most of us with good dental hygiene, the number is more like a day or two.

This means that, if you know the test is coming up, you can simply abstain from cannabis for a day or two, and perhaps be extra vigilant when you brush your teeth. If you need to speed up the process, however, there are things you can do to accelerate the clearing of THC from your saliva. 

How To Clear THC from Your Saliva

Since the window of detection for mouth swab tests is relatively short, it’s a good idea to simply hold off on smoking for a few days leading up to when you suspect the test. Edibles reduce the risk of detection a little bit, but it’s better to just abstain for a couple days rather than take the gamble. Researchers are working on a test with lower ranges, so it’s a good idea not to put yourself at risk for a nasty surprise!

Sometimes, however, you don’t have an advance warning, requiring you to find a quick solution to help you pass the swab. For these time-sensitive instances (like a police checkpoint or a surprise test at work), there are two reliable ways to pass the test.  

Passing A Mouth Swab Drug Test With A Few Hours Notice

As far as surprise drug screens go, the best-case scenario is that you’re going to be tested, say, at work, but you have a few hours before the swab. First, start drinking lots of fluids. Vigorously swish water around in your mouth, and use an non-alcoholic mouthwash if you have some on hand. If you can brush your teeth, absolutely do, and be thorough!

It’s also a very good idea to get a helping or two of some fatty food. Remember, THC is lipid-soluble, meaning it bonds to fat, so eating something with a high fat content can help remove lingering THC from your mouth quickly and effectively. 

Passing a Mouth Swab Drug Test With Little to No Notice

In the worst-case scenario, you get pulled over and don’t have a moment to spare. Don’t freak out just yet: you’ll be prepared after reading this guide. It’s time for some adulteration! 

You might have heard of the adulteration method if you’ve been researching how to pass a drug test: adulterants are chemicals that interfere with a drug test’s ability to read the sample, and there are new and improved ones coming out constantly. This is because there’s an arms race of sorts between drug testing companies and the people trying to beat them: an adulterant works and beats the test, only for a new test to come out that can detect the adulterant’s presence, and the process starts all over again. 

For mouth swabs, the general adulterant of choice is hydrogen peroxide. You can swish some vigorously around in your mouth quickly and adulterate your saliva enough to fool the test. This trick only works for a short period of time, so you have to use it just minutes before you’re swabbed. For this reason, it’s not ideal, but it does work in a pinch. 

We recommend keeping a bottle of Toxin Rid Rescue Wash Mouthwash in the glove box for such instances, as it works quickly and reliably, and certainly tastes better than hydrogen peroxide (ick). Swish with one third of the bottle at a time, spitting between, and pop in a couple of breath mints for good measure.


As far as drug screens go, mouth swabs are pretty easy to beat. They only detect THC for a short time and are easy to pass with flying colors if you know a few days in advance. However, if you’re caught by surprise, you still have options! Keep calm and get your mouth clean as quickly as possible, or deploy an emergency method a few minutes before the test. We suggest stocking up with some cleansing mouthwash—use discount code: 'TestClear10' to get 10% off of all TestClear's detox products site wide! 

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