How Long Does THC Stay in Your Saliva?

Have an upcoming drug test? Worried about the amount of weed in your saliva? Let us help…

If you smoke cannabis regularly, chances are that at some point in your life you have wondered how long THC stays in your system. Maybe you’re worried about routine drug testing prior to starting a new job, or maybe you’re just unsure if/when it’s safe to drive home after smoking a joint.

Unfortunately, there are no hard and fast answers to the question of how long THC stays in your saliva. The exact number will depend on several different factors, including things like body mass index, metabolism, and age. However, by far the most important thing to take into consideration is how often – and how much – you smoke.

See the table of contents selections below to jump directly down and find out how long a saliva drug test can detect marijuana for. Or, for a more complete and well-rounded discussion on the topic, continue reading below.

What is Saliva Drug Testing for Marijuana?

Drug testing is mostly reliant on blood or urine samples. However, some companies are turning to faster and cheaper alternatives such as saliva drug testing for marijuana. This screening technique is used by employers, athletic associations, and even police units to identify the presence of illicit substances.

In a functional sense, saliva can be used to test for drug use in the same way that blood and urine can. Saliva drug tests require the subject to provide a sample, either by spitting or by holding an absorbent pad in their mouth for a short period of time. The advantage of cannabis saliva testing over blood and urine testing is that it is quick, convenient, and non-invasive; it can be done practically anywhere without infringing on the subject’s privacy.

In the last half-decade, scientists have made considerable improvements in methods that optimize THC saliva drug testing.

Another advantage of saliva testing for marijuana is that, since the tests can be done in the presence of another person (unlike urine testing), the possibility of cheating is basically non-existent. These factors make saliva drug testing an ideal tool for use on the roadside, as well as the workplace.

How Does Saliva Drug Testing Work?

Your mouth contains three glands which can produce as much as several milliliters of saliva per minute. The amount of saliva you produce increases or decreases throughout the day by various factors. These factors include hunger, certain drugs and medications, and even emotions like stress and anxiety.


In most instances, it takes about 1–3 minutes to collect enough of a sample to perform an accurate saliva drug test for cannabis. It can sometimes be challenging to get an adequate amount, since many people feel anxious before taking a drug test – which can cause dry mouth.

Certain substances, including marijuana, also produce dry mouth as a side effect. This makes it harder to collect enough saliva to get accurate results. If you need to take a saliva drug test but have a dry mouth, you may be asked to suck on a citrus candy first to help stimulate natural saliva production.

how long does weed stay in your saliva

Once a sufficient sample has been collected, the saliva can be tested for metabolites of alcohol, marijuana, amphetamines, cocaine, opioids, anabolic steroids, and certain prescription medications. The levels of these substances found in saliva are similar to the levels seen in blood during the elimination phase.

DID YOU KNOW? It only takes 1–3 minutes to collect enough saliva to perform an accurate THC mouth swab test.

The marijuana (weed) compound which is most often tested for in saliva is Δ9-tetrahydrocannabinol (THC). This is the chemical that possesses psychoactive properties and produces a high in cannabis. The cut-off point for the presence of THC as deemed by the Substance Abuse and Mental Health Services Administration (SAMHSA) is 50 ng/L for initial testing, and 15 ng/L for confirmation tests.

So… How Long Does THC Stay in Your Saliva?

The best academic reference that we have to go off of in terms of how long weed is detected in the saliva for suggests about 24-72 hours for occasional users, and up to 30 days for frequent users:

  • For occasional users, THC from marijuana can be detected in the saliva for one to three days
  • Among more frequent users, THC can be detected in the saliva for up to 30 days

Why does the rate differ so much?

Marijuana contains hundreds of different compounds that are all metabolized by the body at different rates. When someone smokes marijuana,  THC enters the bloodstream almost immediately and peaks 3–10 minutes after inhalation. With edibles, it can take 1–2 hours for THC to enter the bloodstream (this is because it has to travel through the digestive tract first).

DID YOU KNOW? When you smoke cannabis THC enters your bloodstream almost instantaneously. However, its concentration peaks about 3–10 minutes after inhalation.

One can feel the effects of marijuana for a few hours as the liver slowly breaks down active compounds known as phytocannabinoids. This complex process changes THC into various metabolites, one of the most common being THC-COOH (11-nor-9-carboxy-Δ9-tetrahydrocannabinol).

Around 85% of cannabis metabolites are excreted in the urine and feces over the course of a few days. However, THC is fat-soluble, and can therefore be stored in fatty tissues for long periods of time. Cannabis metabolites, including THC-COOH, can also be reabsorbed into the bloodstream from the kidneys. This means that they can stay in your system much longer than THC itself.

In Summary…

To summarize, the more frequently and the more heavily you smoke cannabis, the more metabolites will build up in your system. Also, it’s worth pointing out that regular or heavy smokers often inhale more deeply, meaning they initially absorb more cannabinoids compared to lighter users.

Smoking more simply means that traces of cannabis will stay in the saliva for longer. The rate of excretion of compounds also depends on things like gender, age, and weight. For example, women seem to be able to metabolize these compounds more quickly than men. And lastly, since THC is stored in fat, the compound is often detectable in overweight individuals for longer periods of time.

Research on How Long Weed Stays in the Saliva

One study on the detection time for THC in oral fluid after regular cannabis smoking cited a maximum of eight days. The study also found that levels of THC-COOH in the urine were not consistent with levels of THC found in saliva; while THC-COOH levels decreased steadily over time in urine, examiners found negative salivary THC samples interspersed amongst positive samples. This suggests that THC levels can rise and fall over the course of a few days after smoking.


Another piece of research on oral fluid cannabinoid concentrations compared the levels of THC and other cannabinoids among frequent marijuana users with that of occasional users. Participants in the study had their saliva checked for THC and other cannabinoids 19 hours prior to smoking. They then smoked under controlled conditions, after which researchers tested them at regular intervals for a 30-hour period. All test subjects tested positive after 13.5 hours, suggesting a minimum time range for the elimination of THC metabolites in oral fluid.

how long does weed stay in your mouth

Making Sense of the Results for Cannabis and Saliva-Based Research

Regarding the above study wherein positive THC screenings were detected among all test subjects at 13.5 hours, it was observed that THC levels among occasional users began to fall after this amount of time, while THC levels among frequent users remained elevated for several hours.

Cannabidiol (CBD) and cannabinol (CBN) levels also dropped more slowly among frequent marijuana users. These chemicals were, however, at undetectable levels in both groups after six and 10.5 hours, respectively. The most significant difference between the two groups involved THC-COOH levels; for occasional smokers, baseline THC-COOH was less than 0.1 ng/L. This number rose after smoking, peaking at a median 17.6 ng/L after five hours. However, among frequent smokers THC-COOH levels were consistently higher, remaining closer to 100 ng/L both before and after smoking.

Recent studies have shown that THC-COOH levels spike immediately after use among infrequent smokers, yet remain stable among heavier users.

All in all, the results of this study suggest that THC-COOH levels appear to peak in infrequent smokers while remaining stable among heavier users. Authors also note that examiners can detect THC in saliva from secondhand smoke, whereas they seemingly cannot with THC-COOH. To summarize, it appears that the amount of time weed stays in your saliva not only depends on how often and how heavily you smoke, but also on which specific metabolites examiners are testing for (THC or THC-COOH).

Can You Reduce the Time That Weed Stays in Your Saliva?

Unfortunately, there is not much you can do to cut the time that traces of weed stay in your saliva. One study on drug testing in oral fluid found that food, drink, toothpaste, and mouthwash did not affect the concentrations of drugs found in saliva 30 minutes after use.

The authors did state, however, that the one thing that seems to lower cannabis concentrations is drinking beer immediately after smoking. Doing this appears to lower THC concentrations one hour after dosing. However, this is not much use if you are considering whether you are fit to drive. Adding alcohol into the mix will only make things worse. There was also no evidence that fasting, exercising, or increasing fluid intake significantly affects levels of THC or THC-COOH in the saliva.

Final Thoughts on How Long Weed Stays in Saliva

The amount of time that THC stays in the saliva depends on how often and how much you smoke. If you are an occasional smoker, examiners may find traces of THC in the saliva for 1–3 days after smoking. However, if you are a regular, heavy smoker, marijuana can be detected up to a month later. This is most likely due to an accumulation of THC-COOH stored in fatty tissues.

Drug tests may be carried out by an employer, or even at a roadside test if the police have reason to believe someone is driving under the influence. For those that find themselves with any doubt regarding their ability to operate machinery or drive safely after using marijuana, do not drive, and do not take any chances. Not only could you pose a risk to yourself and others, but if your saliva tests positive for THC, you could find yourself in a world of legal trouble.

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