Fraser Horton
Fraser Horton
Last Updated on July 21, 2021

The relaxation of the laws regarding marijuana use in most states has loosened things up a bit and boosted the overall consumption of weed, as well as the people’s interest in cannabis, in general. However, despite the legality of cannabis use changing, employers still order mandatory drug use screens that include cannabis, especially in employment sectors where safety is of the utmost importance. 

By far, the urine drug test is most commonly used for drug screening in the workplace, but other types of drug tests are also being used, such as the saliva test. This is a quick and easy testing method, and much less risky than other types of drug screens. Therefore, in this article, we’ll talk more about saliva tests and how far back they can detect the presence of THC.

How Long Does Marijuana Stay in the Body?

Shortly after you consume marijuana, its active ingredients, THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol), as well as other cannabinoids, terpenes, and other compounds enter the bloodstream and start circulating and doing their thing. 

Then they get carried to the liver where the enzymes break them down into byproducts called metabolites that attach themselves to the fat cells in the body. That’s because the cannabinoids and their metabolites are fat-soluble.

THC is stubborn this way and the THC metabolites will linger in the body fat for an extended period of time until it gets gradually eliminated. That’s why cannabis can be detected in the body for up to 90 days. However, this also depends on other factors, such as: 

  • Frequency of use – chronic users will have a greater amount of THC stored in their body;
  • The strain you consume – high-THC strains create more THC metabolites;
  • Body fat percentage – it’s thought that most people with higher body fat will store THC metabolites for longer, but there can be exceptions;
  • Your own metabolism – some people have a naturally high metabolism that eliminates waste products more quickly.

Since THC metabolites tend to live snugly in your body fat for a prolonged period of time, most drug tests were designed to detect metabolites instead of THC itself. The metabolite called THC-COOH is what most drug screens look for.

How Do Saliva Tests Work?

Other types of commonly used drug tests, such as urine tests and hair follicle tests, look for the THC metabolite, but the saliva test is different because it detects THC itself, or the parent drug, as labs usually refer to it. When you consume weed orally or by smoking it, THC gets stored in the oral mucous membrane and gets released directly into the saliva.

The saliva test, also known as the oral fluid test, is used to screen not only for cannabis, but also for other types of drugs –  amphetamines, opiates, cocaine, barbiturates, ecstasy, phencyclidine, methamphetamine, methadone, and benzodiazepines. The tester will take a sample of your saliva by swabbing your oral cavity and underneath your tongue where your major salivary glands are.

The saliva swab is then tested for the presence of THC by using the enzyme immunoassay technology, and any positive results are then retested using more accurate methods such as liquid chromatography and mass spectrometry.

The presence of THC itself for the saliva drug test and THC metabolites for the other types of drug tests is measured in nanograms per milliliter (ng/ml) and each type of drug test has its own cutoff levels. According to the Substance Abuse and Mental Health Services Administration’s (SAMHSA) proposed guidelines, the cutoff level for saliva tests is 4 ng/ml for the initial testing, and then 2ng/ml for confirmatory testing of the swabs that come back positive.

What Is the Detection Time of THC in Saliva?

The fact that saliva tests look for THC instead of its metabolites means that the detection window is a lot smaller compared to urine tests and hair follicle tests.

Typically, for occasional users, the average timeframe of detection for THC is up to 72 hours or 3 days before THC is completely eliminated from the oral cavity. However, for chronic users who consume weed at least once a day, the amount of time can stretch up to 29 days.

Again, the amount of THC in your saliva will largely depend on how much you have consumed and how potent the weed was.

Do Saliva Tests Detect CBD?

Saliva drug tests were not designed to detect CBD (cannabidiol) because it’s a non-psychoactive cannabinoid. As of yet, there isn’t a standard for measuring the quantity of CBD present in the human body. Additionally, hemp-derived CBD products have been federally legal in the US for a few years now as long as they contain less than 0.3% THC, making the need for testing for CBD redundant.

On the flip side, if you tend to use marijuana strains that are high in CBD, you must know that their THC content will vary. Depending on how often and how much you smoke, this may put you at risk to fail any type of drug test, including a saliva test.

How Does the Saliva Drug Test Compare to Other Kinds of Drug Testing?

The saliva test is similar to the blood test in that they both look for THC instead of the THC-COOH metabolite, which also means that they both have the shortest detection windows. While the saliva test can detect THC for up to 3 days, the blood test is used to detect recent use, from 12 to 24 hours.

Urine tests and hair tests both detect the THC-COOH metabolite, meaning that their detection windows are much longer. Urine tests can detect cannabis use from 3 days to over 30 days, while hair tests go even further back – up to 90 days to detect long-term use.

How to Pass a Saliva Drug Test

Saliva drug tests are considered much easier to pass than urine tests and especially hair tests. Whatever your frequency of use is, if you have an upcoming saliva test and want to avoid getting a positive result, it’s best to abstain from consuming cannabis for the following few days so you can give your oral cavity time to detox. In most cases, this does half the job.

Another good idea is to up your oral hygiene by brushing diligently three times a day and making sure you clean the insides of your cheeks and under your tongue well. Rinsing with a good mouthwash is also helpful, but be careful of overdoing it because it can lead to irritation of the gums.

Finally, you can also try eating more fatty foods a few days before the test. The idea is to boost the absorption rate of THC because THC is fat-soluble. This will cause the metabolite levels in your body to rise, which is exactly what you want. Saliva tests don’t look for metabolites anyway, so boosting the absorption rate of THC will eliminate it faster from your oral cavity.

Conclusion – The Saliva Test Has One of the Shortest Detection Windows

We’re not recommending that you cheat on your drug tests – but if you’ve been surprised at work with an announcement for a saliva drug test, don’t stress out. Compared to other types of drug tests, the saliva test is much simpler and easier to pass because THC doesn’t stay in your oral cavity for that long. Still, abstaining from weed is probably your best bet in passing these types of drug tests.

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