Have an upcoming drug test and 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 before starting a new job, or perhaps you have simply debated whether you are safe to drive home a few hours after smoking a joint.
Unfortunately, there are no hard and fast rules or simple answers to these questions, because how long THC stays in your saliva depends on a number of different things. Factors such as your gender and body mass index can both affect how quickly you metabolize marijuana, for example. However, by far the most important thing to take into consideration is how often and how much you smoke.
What Is Saliva Drug Testing?
In the past, drug testing was reliant on blood or urine samples. However, this has changed in the last decade or so, as scientists have made considerable improvements in alternative methods such as saliva drug testing. This technique is now widely used by employers, the police, and even athletics associations trying to identify illicit substance use in their subjects.
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 few minutes. The advantage of saliva testing over blood and urine testing is that it is quick, convenient, non-invasive, and can be done 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.
Since saliva testing can be done in the presence of another person, it also eliminates the possibility of switching samples to give a false negative. These factors make saliva drug testing an ideal tool for use on the roadside and in the workplace, and it is becoming more popular all the time.
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 can increase or decrease by various factors. These include hunger, emotions, and certain drugs and medications.
It can take 1–3 minutes to collect enough saliva to perform an accurate test. It can sometimes be challenging to get an adequate sample since many people feel anxious before taking a drug test, which can cause dry mouth.
Certain substances, including marijuana, can also cause 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 and have a dry mouth, you may be asked to suck on a citrus candy first to help stimulate your saliva production.
Once a sufficient sample has been collected, it can be tested for the presence 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 compound which is most often tested for in saliva is Δ9-tetrahydrocannabinol (THC), the chemical which gives cannabis its psychoactive properties. The Substance Abuse and Mental Health Services Administration (SAMHSA) tests for a compound known as THCA. The cut-off point is 50 ng/L for initial testing, and 15 ng/L for confirmation tests.
So… How Long Does THC Stay in Your Saliva?
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 as it has to travel through the digestive tract first.
DID YOU KNOW? When you smoke cannabis, THC enters your bloodstream almost immediately but peaks 3–10 minutes after inhalation.
One can feel the effects of marijuana for a few hours as the liver slowly breaks down its active compounds. This complex process changes THC into various metabolites. One of the most commonly measured of these metabolites is called 11-nor-9-carboxy-Δ9-tetrahydrocannabinol, or THC-COOH for short.
Around 85% of cannabis metabolites will be excreted in the urine and feces over the course of a few days. However, THC is fat-soluble, and some will be stored in fatty tissues and organs such as the liver, lungs, and spleen. Cannabis metabolites such as THC-COOH can also be reabsorbed into your bloodstream from your kidneys, meaning that these chemicals can stay in your system much longer than THC itself.
The more frequently and the more heavily you smoke, the more metabolites will build up in your system. Also, regular or heavy smokers may inhale more deeply and hold the smoke in their lungs for longer. This means they initially absorb more cannabinoids compared with lighter users.
Smoking more means that traces of cannabis will stay in your saliva for longer. The speed of the excretion of compounds also depends on your gender and weight. Women seem to be able to metabolize these compounds more quickly than men, and since THC is stored in fat, it may be excreted more slowly if you are overweight.
Research on How Long Weed Stays in Your Saliva
One study on the detection time for THC in oral fluid after regular cannabis smoking found that the levels of THC-COOH in 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 between frequent marijuana users and occasional smokers. The 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.
Making Sense of the Results for Cannabis and Saliva Based Research
Authors of the study found that all of the subjects tested positive for THC at 13.5 hours after smoking, regardless of the frequency of their cannabis use. After this, the mean THC levels for occasional users fell, while THC levels among frequent users remained elevated.
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, for 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 in infrequent smokers, yet remain stable in 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.
So 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 chemicals 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.
Research has shown that food, drink, toothpaste, and mouthwash does not always affect the concentrations of [THC] found in saliva 30 minutes after use.
The authors state 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 is no evidence that fasting, exercising, or increasing your fluid intake significantly affects the levels of THC or THC-COOH in your saliva.
Final Thoughts on How Long Weed Stays in Your Saliva
The length of time that THC stays in your saliva depends on how often and how much you use. If you are an occasional smoker, examiners could find traces of THC in your 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 because of an accumulation of THC-COOH stored in fatty tissues. Simply put, the amount of time that THC stays in your saliva depends on how often – and how much – you smoke.
Drug tests may be carried out by your employer routinely or following a motor vehicle accident. You could also be stopped for a roadside test if the police have reason to believe you are driving under the influence. If you ever find yourself in any doubt about your ability to operate machinery or drive safely after using marijuana, play it safe. 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 whole world of trouble.