THC in Saliva: How Long Does It Stay?

If you’ve recently used cannabis and are facing a saliva drug test, it’s natural to wonder: how long does THC stay in the saliva glands? The short answer is anywhere from 24 to 72 hours, depending on your usage habits and other factors.

Saliva tests are increasingly used for roadside drug screening and workplace testing. They’re designed to catch recent cannabis use, not long-term habits. But while THC may only stay in your saliva briefly, even a small trace can lead to a positive result.

How Does THC Get into Saliva?

When you smoke or vape cannabis, THC enters your mouth directly through the smoke. Some of it sticks to your gums, teeth, and cheeks, and small amounts are absorbed into the saliva glands. This is why saliva tests can detect cannabis so soon after use—often within minutes.

Unlike blood or urine tests that look for metabolites (breakdown products), saliva tests detect active THC, which reflects very recent use.

How Long Does THC Stay Detectable in Saliva?

The detection window depends largely on how much and how often you use cannabis.

Occasional users (once or twice a week): 1 to 2 days
Frequent users (3–5 times a week): Up to 3 days
Daily or heavy users: Possibly longer than 72 hours, but rare

In most cases, THC disappears from saliva within 24–48 hours, especially if use was light or occasional.

What Affects How Long THC Stays in Your Saliva?

Several factors influence how long THC lingers in your mouth:

Frequency of use – The more often you use cannabis, the more it builds up in your body, including in your saliva. Daily users are more likely to test positive after a longer period.

Dose and strength – High-potency strains or heavy consumption sessions (e.g., several joints in one night) result in more THC being deposited in the mouth.

Hydration and oral hygiene – Rinsing your mouth, staying hydrated, and brushing your teeth may help reduce THC traces in your mouth more quickly, but these are not foolproof methods.

Method of use – Smoking and vaping introduce THC directly into the mouth. Edibles are much less likely to be detected in saliva tests unless THC residue enters the mouth by other means.

How Do Saliva Drug Tests Work?

Saliva drug tests typically involve a swab placed inside the mouth for 1–2 minutes. The sample is then tested for the presence of THC above a set threshold (usually 10–25 nanograms per millilitre). In the UK, roadside drug testing devices used by police are calibrated to detect THC at levels that suggest recent use.

If the test is positive, you may be taken to a police station for a blood test to confirm the result.

Can You Beat a Saliva Test?

There’s no guaranteed way to “beat” a saliva test if you’ve used cannabis recently. Some people try using mouthwashes, gum, or hydrogen peroxide, but there’s little evidence these are effective.

The most reliable method is time. Avoiding cannabis use for 2–3 days before a test is usually enough for occasional users. Heavy users may need longer.

THC and Driving: What You Should Know

In the UK, cannabis is a Class B drug, and driving under its influence is a serious offence. Police use saliva testing at the roadside to screen for drug-driving. If you’re over the legal limit for THC (2 micrograms per litre of blood), you face:

A minimum 12-month driving ban
An unlimited fine
Up to 6 months in prison
A criminal record

Even if you feel sober, THC can still be present in your system—and you can still be charged.

Final Word

THC stays in the saliva glands for 24 to 72 hours, depending on how much and how often you use cannabis. Saliva tests are designed to detect recent use, so even a single joint could lead to a positive result within that window.

If you're facing a saliva drug test—whether at work or on the road—avoid using cannabis for at least 2 to 3 days beforehand. If you're a frequent user, you may need longer.