How A Saliva Test (Mouth Swab) Works

Of all the tests for drugs prevalent in the modern workplace, the saliva test, also popularly known as the mouth swab test is growing in popularity.

How It Works

How it works is ultimately very simple. Most saliva tests/mouth swab tests (also called an oral fluid test) work by collecting a small amount of saliva in a sterile tube. It’s followed by careful processing at a laboratory where the lab techs will search the sample for chemical markers. It is much like any other test for chemicals in a body fluid sample.

Popular methods of gathering the subject’s slobber include absorbent pads, the application of certain chemical solutions and monitoring for a color change to indicate a positive or negative result. Absorbent pads and chemical solutions are however known to skew results of immunoassays, and research is being conducted to iron out these kinks in the process. Once the sample is in the lab, the lab techs have a dizzying array of tools and methods by which to test for a great number of substances. Some particularly fast tests (usually administered by impatient employers) require that a swab be placed in the subject’s mouth for two minutes and produces a result right there on the spot.

Testing for ethanol and its three main metabolites (methanol, ethylene glycol and diethylene glycol) in saliva can quickly identify recent consumption of alcohol to a frightening degree. Further drug metabolites are beginning to be detected more frequently in saliva. Mouth swab tests can also be used to detect other drug metabolites, such as morphine, other benzodiazepines, cocaine and of particularly note, cannabis, albeit not as accurately as it might in a urine test (note – people use synthetic urine to overcome most urine tests).

These tests allow employers to scan for drug use from the previous few days. It can be administered as frequently as the dreaded urine tests, up to and including that old chestnut of “reasonable suspicion” or the classic line of “random testing”. Saliva tests are particularly popular for testing for on the job drug use as the samples are particularly relevant the more recently the chemicals were ingested. Currently, there is little standardization among diagnostic devices, meaning that results will vary depending on which lab and tool set was used to analyze the sample. Various agencies are already working to amend this situation.

Ways to Pass a Saliva Test

Luckily for honest workers, there are a few simple techniques to pass a mouth swab test. Since the chemical markers from drug use being tested reside in the mouth, good dental hygiene is a must. Brush your teeth multiple times the day before the test, floss like you were taught to and don’t forget to use mouthwash.

The easiest way to pass is to not partake in one’s chemical of choice for a certain amount of time and letting their all-natural immune systems clean out the chemicals for them. However, it should be noted that some chemicals leave the mouth quicker than others. Marijuana and hash, for instance, leave the mouth the quickest, usually inside of twelve to twenty-four hours. Cocaine takes around a day while opiates require two to three days. Meth and ecstasy tend to take between two and four days to leave the mouth while alcohol (including the hooch in mouthwash) take a mere six to twelve hours to leave the mouth.

With this in mind, it behooves the honest worker to lay off their enjoyments for a certain period before the tests in addition to the proper dental hygiene to stack in the deck in your favor. Even better, saliva tests are currently somewhat unreliable and easier to beat than urine and blood sample tests. While scientists are currently laboring to overcome these issues, saliva tests remain popular. It is likely going to remain popular because of their non-invasiveness (and thus lowered risk of complaints and lawsuits from workers being forced to take them) and their ease of use on employers. On top of this, it takes less time for the results to come.

The tests go easiest on the users of alcohol and marijuana though even users of those chemicals may way to take precautions if they anticipate taking a mouth swab test. For surprise tests (and with those above on the spot result tests, surprise tests are becoming ever more popular with paranoid employers), one should keep powerful mouthwash on hand, somewhere nearby them. There are some specialized products out there. But the more reliable ones can instantly detoxify the mouth and allow for a simple, easy cleaning out of any telltale chemical markers.


The saliva test is growing quickly in popularity among employers who don’t trust their employees. While honest employees have much to fear from the mouth swab test, there are ways around it. How it works is by simply taking samples of the subject’s saliva and testing them for chemical markers. There are ways to pass a saliva test, but the easiest one is to hold off on indulgence for a prescribed period. With all this in mind, saliva tests then become much less intimidating, allowing honest workers to hold on to honest jobs in this increasingly paranoid time.

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