How long will you be impaired after using cannabis? How long before you will pass drug testing after using the drug? Photo by Dimitri Bong on Unsplash

How long does cannabis impairment last?

You enjoy a joint of cannabis now again. No judgement here, that’s your choice, but if you’re the type of person who’s reasonably responsible, you’ll want to make sure your pleasure doesn’t impact your safety or someone else’s safety. In other words, you’ll want to make sure that you’re not impaired before driving, going to work or doing any other activity where concentration and fine motor skills are required.

So, how long will you be impaired after using cannabis? How long before you will pass drug testing after using the drug?

The answers to these questions are somewhat controversial and a matter of conjecture, but new research by the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney has suggested how long cannabis users are likely to be impaired. Findings from the report were highlighted in the media recently. The key finding from the research is that users are impaired for between three and 10 hours after taking moderate to high doses of cannabis.

The research was completed by analysing 80 scientific studies conducted over the past 20 years into the effect of THC on driving performance. THC is the psychoactive component of cannabis.

An important thing to note is that the effects, and therefore the level of impairment and time required for a person to become unimpaired, can vary significantly. For example, the dose taken, how the cannabis was used and how often the person has used the drug before will all impact the time. Individual factors also play a part.

“Our analysis indicates that impairment may last up to 10 hours if high doses of THC are consumed orally,” says the study’s lead researcher Danielle McCartney.

“A more typical duration of impairment, however, is four hours, when lower doses of THC are consumed via smoking or vaporization and simpler tasks are undertaken.”

How long before you will pass drug testing after using cannabis?

So, how do the findings from this research stack up against research into drug testing timelines for cannabis?

According to the Alcohol and Drug Foundation, “Random roadside saliva tests can detect THC for around twelve hours after use for people who use cannabis infrequently or ‘recreationally’. However, for people who frequently use cannabis THC can be detectable for around 30 hours.”

While this doesn’t match up with the research by the Lambert Initiative, the gap is not enormous. It’s important to note that the gap for urine testing is far greater. People who use cannabis frequently can have THC detected in their urine sample for around a month after cannabis was last used, because the body stores THC in fat cells for a period of time. This is one reason why Integrity Sampling recommends saliva drug testing over urine drug testing.

One thing that is not argued by experts is the impact THC can have on safety. For example, two large European studies found that drivers with THC in their blood were around two times more likely to be responsible for a crash resulting in a fatality than a person unaffected by drugs or alcohol. Those with THC in their blood were also three to seven times more likely to be responsible for an accident on the road than unaffected drivers.

Food for thought.

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How long will you be impaired after using cannabis? How long before you will pass drug testing after using the drug? Photo by Dimitri Bong on Unsplash

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Michael

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Michael is the founder of Integrity Sampling and is responsible for overseeing all national operations. He is based at Integrity Sampling's head office in Thomastown and is also responsible for the co-ordination of drug and alcohol testing within Victoria, assisting in the implementation of drug and alcohol (fit for work) policies and the presentation of drug and alcohol education and awareness programs. You can connect with Michael Wheeldon on LinkedIn

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