Research from the University of Sydney in Australia has recently defined the durations of impairment after smoking or vaping THC. 

This information could provide insights into how cannabis interacts with our bodies. However, it also brings into question several complications surrounding legal restrictions across the world. 

One example is drug-driving laws and how long THC stays present in your system even after the initial high. 

The study, consisting of an analysis of 80 scientific studies, distinguished a “window of impairment” regarding how long marijuana intoxication lasts and when users can appropriately resume “safety-sensitive tasks,” including driving, after using cannabis. 

But what do these findings really mean, and what are the future implications? Today, we’re here to answer these questions and more. 

Cannabis Intoxication Duration

This comprehensive analysis that finally answers the age-old question “how long does weed last” comes from the dedicated efforts of a group of researchers led by Dr. Danielle McCartney from the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney. 

This department supplies national and international leadership for scientific research of medical marijuana and in “the discovery and development of cannabis-based medicines.” 

According to an article posted on the university’s website, the study found that the exact time span for impairment relies on a collection of specific criteria, including the THC dose, method of ingestion (i.e., if it was taken orally or inhaled), whether users smoke weed everyday or only sometimes and the specific requirements of the tasks at hand while under the influence. 

These findings have been published in the Neuroscience & Behavioral Reviews. According to the article, the data “represents the first such meta-analysis” into cannabis intoxication duration. It comprises and distills information from 80 different scientific studies surrounding THC-induced impairment spanning the past 20 years.

Dr. Danielle McCartney from the Lambert Initiative for Cannabinoid Therapeutics. University of Sydney

“THC is known to acutely impair driving and cognitive performance,” Dr. McCartney explains in the article. Still, many users are unclear as to how long this impairment lasts and when they can safely and responsibly resume “safety-sensitive tasks,” such as driving, after consuming weed. 

The analysis shows that cannabis impairment can last upwards of 10 hours with higher THC doses consumed orally. However, a more typical impairment duration is 4 hours when ingesting lower THC doses by smoking or vaping. 

“This impairment may extend up to six or seven hours if higher doses of THC are inhaled and complex tasks, such as driving, are assessed,” McCartney states. 

For context, a “moderate THC dose” in this study is about 10 mg. However, researchers say that amounts considered moderate to regular users “could be high” for less frequent users. 

“We found that impairment is much more predictable in occasional cannabis users than regular cannabis users,” co-author of the study, Dr. Thomas Arkell, explained. “Heavy users show significant tolerance to the effect of cannabis on driving and cognitive function, while typically displaying some impairment.” 

Additionally, the authors observed that regular weed users might ingest more to achieve a more intense effect, resulting in an equal level of impairment. 

Ingestion Method Matters

It’s no secret that there are several varieties of cannabis products currently available on the market. Whether you are a die-hard fan of tried and true classic flower or a concentrate connoisseur, how these different items interact with your body directly impacts intoxication duration. 

According to the University of Sydney article, THC in the form of sprays, capsules or oils, and those ingested orally cause impairment to take longer to set in and lasts “significantly longer” than if users were to inhale through more traditional methods, such as smoking or vaping. 

Additionally, when utilizing more conventional methods, various techniques for making weed last longer, such as using more potent bud or rolling twax joints, will also impact your level of intoxication and the duration of the marijuana’s effects. 

With this insight, researchers state that these findings could have “implications” for drug-driving laws.

cannabis intoxication duration and ingestion methods relationship

“THC can be detected in the body weeks after cannabis consumption while it is clear that impairment lasts for a much shorter period of time,” Academic Director of the Lambert Initiative, Professor Iain McGregor, explains in the article. “Our legal frameworks probably need to catch up with that and, as with alcohol, focus on the interval when users are more of a risk to themselves and others.”

McGregor continues that prosecuting users solely based on them having THC present in their blood or saliva is “manifestly unjust.” 

“Laws should be about safety on the roads, not arbitrary punishment,” he describes. “Given that cannabis is legal in an increasing number of jurisdictions, we need an evidence-based approach to drug-driving laws.” 

The study comes after recent research by Dr. Thomas Arkell and colleagues demonstrating that cannabidiol, or CBD, a non-psychoactive and “medically active” component in cannabis, does not cause impairment while driving. 

What are the Current Drug-Driving Laws? 

In the context of Canadian law, specifically, operating a vehicle while under the influence of marijuana is considered a criminal offence.

Bill C-46 passed in June 2018, which added federal laws and penalties to the Criminal Code of Canada surrounding driving while impaired. 

As such, provinces and territories have implemented varying laws surrounding cannabis and driving to complement the new federal ones. 

According to Bill C-46, the criteria for DUI charges include: 

  • Having between 2 and 5 nanograms of THC per ml of blood within two hours of driving results in a $1,000 fine. 
  • Having over 5 nanograms of THC per ml of blood within two hours of driving may be considered a “summary or indictable offence,” with punishments ranging from a $1,000 fine to a maximum of 10 years jail time for repeat offenders. 
  • Having both alcohol and THC in your system is considered a “hybrid offence, indictable or summary” and would also be punishable by a $1,000 fine to a max of 10 years prison time for repeat offenders. 

However, with these findings from the Lambert Initiative for Cannabinoid Therapeutics, such legislation may not be as simple as believed since THC remains in your blood and saliva for extended periods. 

For the future, further research is needed to find the best approach for correctly detecting when THC was consumed and how this impacts the ability to drive. 

Are There Techniques for How to Sober Up From Weed?

If you’re no stranger to the world of weed, you’ve likely been in a situation where you might have bitten off more than you can chew. Be it figuratively, in the context of smoking too much weed, or literally, when ingesting cannabis edibles

Either way, knowing how to sober up from weed can be an incredibly valuable life skill for tokers of all experience levels. 

Eating food to supplement your blood sugar, staying hydrated, taking some CBD and sleeping are all effective methods for helping to ride out your high safely and effectively. That said, individual factors such as weight, tolerance level, frequency of use, the particular potency of the weed and the ingestion method will all play critical roles for how long your high will last. 

If you’re looking for some friendly tips for how to sober up from weed, check out our helpful tips on how to sober up from weed!

Cannabis Intoxication Duration – Implications for the Future

Comprehensive data regarding the duration of cannabis impairment, such as those found by researchers at the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney, provide crucial insights into how our bodies absorb and interact with cannabinoids. 

Essentially, a “window of impairment” can last anywhere from 4 to 10 hours, depending on the THC concentration and delivery methods, such as smoking, vaping, or more potent products, such as THC oral sprays and edibles

However, how long THC remains in your system even after the effects have worn off is worth considering, especially in the face of the law. This information is especially important when discussing international drug-driving laws and their enforcement. 

As Professor Iain McGregor aptly stated, “laws should be about safety on the roads, not arbitrary punishment.” As such, it is crucial to perform an evidence-based approach to drug-driving laws. 

Implementing these changes and adjusting testing to reflect how long THC has been in our systems accurately should the priority. However, the how of it all remains up in the air. 

Still, such changes will ultimately serve to keep pedestrians and fellow drivers safe, cut down on unnecessary prosecutions, and provide further insights into the best approaches surrounding the safe consumption of weed!

Herb Approach News is the media division of the cannabis health company Herb Approach. Through this medium, we are determined in providing insight on everything cannabis related, from news to commentary, from tips to guides on practical consumption, a whole lot more. Have a question? Email us at [email protected]