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For many of us that are not lucky enough to live in places with a legal, regulated cannabis industry, there is still a risk of arrest and even imprisonment for possessing or using cannabis. Even in places with legal cannabis, a positive drug test can lead to denial of state benefits, loss of your career, or even the risk of having your children taken away from you!

Positive drug tests for traces of cannabis don’t necessarily mean that the individual is intoxicated at the time of testing. But this overwhelmingly crucial point is often ignored, and there are plenty of cases of people falling foul of the law for having the tiniest traces of cannabinoid metabolites show up on tests.


As we’ll see here, tests can still show up positive several days or even weeks after you last consumed cannabis! It’s best to be as well-informed as possible – so let’s take a look at what we know:

Detection Time of Cannabinoids in Saliva

Saliva-based drug tests are becoming more and more common. In particular, police in Europe and Australia have been conducting roadside saliva testing for traces of cannabis for several years. It’s one of the faster methods, as it can be done at the side of the road and results generally arrive in just minutes. It can also be highly sensitive, recording levels as low as 3 ng/ml.


THC and its metabolites are eliminated from the saliva quickly – in as little as 24 hours, in some cases. However, heavier users may find that traces remain in the saliva for up to 72 hours, or even as long as a week.


This means that if your saliva is tested, you may pass if you haven’t consumed cannabis for at least 24 hours – but it’s probably safer to assume that you need a few days to really get your “oral fluid” test-worthy!

Detection Time of Cannabinoids in the Bloodstream

Blood tests to detect cannabis are a lot rarer, as they are expensive and much harder to carry out than saliva testing. As well as this, traces of cannabinoids are flushed from the blood almost as rapidly as with saliva, so law enforcement generally considers blood testing to be useful for only a short window of time.


According to NORML, cannabis compounds can only be detected in the blood for 12–24 hours for one-off use, but can remain in the blood for as long as 2–7 days for heavier, more regular users. One point to remember is that blood testing shows presence of THC itself, unlike many other forms that show presence of THC metabolites (compounds left after the body has processed THC).

Detection Time of Cannabinoids in the Urine

The urine test for drugs is probably the most widespread of all, and is the bane of workers in dozens of different industries, in countries all over the world. While some might argue that on-the-job drug testing is a good thing, urine testing can show presence of drugs long after any psychoactive effect has ended.


So there are countless tales of people losing their jobs because they had the audacity to smoke a joint at the weekend rather than sticking to the good old, government-prescribed option of beer or hard liquor!


In any case, urine testing is more of a problem for heavy, regular users than for occasional users. NORML states that for occasional users, retention time of THC metabolites in urine is around 2 days. For heavy users, it could take as much as 100 days for metabolite levels to drop to undetectable amounts!

There are other ways to test for presence of cannabinoids and other drugs, beyond the three methods we’ve outlined above. As well as blood, urine and saliva, there are also tests for sweat and hair – but these are much rarer and unlikely to be an issue for most of our readers.


Let us know if you’ve been tested for drugs, and how it worked out for you, in the comment section below!


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