Saliva testing relies on the same principle as any other drug test. When you use a drug, it breaks down into other compounds in your body. One can find these metabolites in saliva, urine, and blood. They are even deposited onto your hair follicles. Labs can then test these elements by using a simple immunoassay, which looks for either the drug itself or one of these metabolites .
How Does it Work?
In the event of an oral saliva test, you will be instructed to wait in a room for at least ten minutes where you’re not allowed to eat or drink anything. A technician will then come in and use a swab, which can be any instrument, to take a saliva sample. They’ll usually take this from the gum line or under your tongue, where the compounds are more likely to gather and aggregate. The sample is then put into a container and sent off for testing.
Some new saliva tests have the test on the swab, and you can instantly get your results for the panel of drugs the test is looking for. Other tests may require the sample to be sent off to a lab, in which case you will have to wait approximately 24 to 48 hours to get your results.
The main reason the saliva screening is becoming more popular is that it is cheaper and easier to administer than a urine test. It can be performed with very little notice, and your employer can get the results within minutes. The test only costs a couple of dollars and is reliable enough for most uses. The main drawback of the test is that there is a very narrow detection window, and it can only measure drug use within the past couple of days. These limitations mean that giving any advance notice of a saliva test can lead to plenty of negatives due to people abstaining from taking substances for a short amount of time.
Using Mouthwash to Pass a Saliva Screening
There are many articles online about how you can use mouthwash to pass a drug test, with recommendations for the best mouthwash for drug tests and other tips and tricks. The unfortunate truth is that mouthwash is highly unlikely to help you pass a saliva test, mainly due to how the technician takes the saliva.
There is a general guideline for saliva tests that the donor must have nothing in their mouth for ten minutes or more before the technician takes the sample. The reason for this is to allow the mouth time to recalibrate and for new saliva to be secreted. Remember, the test isn’t looking for metabolites in your mouth; it’s looking for them in your saliva, which your mouth secretes continuously. So even if you do rinse your mouth with mouthwash before the test, it won’t do anything to prevent fresh saliva from being gathered after the ten-minute wait period. This process means that any method that relies on you tricking the test by adulterating your saliva with peroxide, bleach, or mouthwash won’t work. Any other claims to the contrary rely on the technician conducting the test not to do their job correctly. And you should always plan on the technician being proficient in their task.
What Are the Alternatives?
Now that we’ve saved you money, which would have otherwise been spent to buy mouthwash for a drug swab test, let’s look at any other alternatives that you can use to pass your saliva drug test.
The most obvious alternative is to not use drugs, at least within the detection window of the saliva test. Luckily, most drug compounds get excreted out of your body relatively quickly and can’t be detected after a relatively short time-frame. In general, most drugs can only be detected in saliva between one-to-four days after your last use.
However, it’s important to note that THC  can linger in your system much longer, especially if you’re a heavy or long-term user. The reason for this is that your body takes a certain amount of time to process THC and excrete it. If you build up the amount of THC in your body, it will take longer for the THC to get processed, since your body already has a backlog of THC to get rid of. Luckily, it appears that most saliva tests can only detect THC use within the last 24 hours even for heavy users. The bottom line is that you need to carefully consider the length of time between your previous use and the day of the test.
Saliva tests can be administered with little or no warning and can give results within minutes. Luckily, there is a very narrow window in which these tests can detect the presence of drugs, so if you know about the test beforehand, you can easily abstain for a day or two and easily pass the test.
There are many recommendations to use adulterants  or dilutants such as specialty mouthwashes, gums, and even hydrogen peroxide to cheat the test. Still, these rely on the technician administering the test incorrectly. In general, no matter what you have in your mouth will be flushed away within ten minutes, allowing the technician to take an unadulterated sample of clean, fresh saliva, rendering any mouthwash or gum irrelevant.
If you’re willing to bank on the technician not waiting for those ten minutes, then indeed, mouthwashes can be useful in masking the presence of drugs. Whether you want to put your job on the line by betting on another person’s competence is a decision you’ll need to make for yourself.