Many cannabis users have always wondered how long the high from cannabis actually lasts. It is an eternal question that has now been answered by some scientists. In a study published in Neuroscience & Biobehavioral Reviews in 2021, researchers led by Danielle McCartney from the University of Sydney discovered a "window of impairment" that depends on the THC dose, the method of use and previous experience with cannabis use.
The high lasts 4-5 hours for most users after taking 20 mg of THC. The high from a lower dose usually lasts 3 hours, while when dabbing or eating cannabis, the effect can last 6-10 hours.
McCartney and her colleagues conducted a comprehensive analysis of 80 scientific studies on cannabis dosage and intoxication. However, the focus of the study was on the effect of the cannabis high on driving ability and the work concentrated mainly on answering this question.
The researchers found that cannabis users regained most of their driving ability within five hours of inhaling 20 mg of THC. Users who had ingested the same amount of cannabis via food took longer to regain their driving skills.
The researchers could generally see from the results that Δ9-THC can impair driving performance. However, it turned out that there is obviously no universal answer to the question of how long the high lasts. Several factors have to be taken into account.
The differences between inhaled and ingested THC were significant. As is generally known, the effect of cannabis starts within a few minutes when inhaled. When cannabis is ingested through drinks or food, it can take up to an hour or more before the effect is felt.
The researchers were able to determine that smoking or vaporising 20 mg of THC impairs a driver's reaction time for about four hours. Ingesting 20 mg of THC via a food or drink impairs reaction time for about eight hours, twice as long. The study data also showed that the reaction time of a THC-impaired driver was not dramatically reduced, however.
The high from edibles sets in later and lasts longer
"Our analysis shows that impairment can last up to 10 hours when high doses of THC are consumed orally," said McCartney, who works with the Australian University's Lambert Initiative for Cannabinoid Therapeutics. However, a typical duration of impairment, or effect, is 4 hours when low doses of THC are smoked or vaporised, he said.
"This impairment", which cannabis users experience as high, stoned, tired, creative, exciting or happy, can last up to 6-7 hours when higher doses are consumed. In the context of the study, 10 mg THC was considered a moderate dose. A moderate dose for an experienced user, however, can also be a high dose for an occasional user, the researcher explains.
Co-author Dr Thomas Arkell, also of the Lambert Initiative, said: "We found that impairment is much more predictable in occasional cannabis users than in regular cannabis users. Heavy users show significant tolerance to the effects of cannabis on driving and cognitive function, while typically showing some impairment."
The secret behind the duration of a high: everyone is different
A large part of the reaction to cannabis depends on the respective biological conditions. In addition, different strains of cannabis have different effects. One strain produces a relaxing sleepy high, while another strain makes you awake and focused. This is well known, but it does not mean that a strain you consume will automatically have the same effect on your friends.
Why do we experience the effects of cannabis so differently?
The different experience has something to do with the human endocannabinoid system (ECS). This allows cannabis to affect each user differently.
The endocannabinoid system is a network of receptors, lipids and enzymes that help the body maintain internal balance and regulate various bodily functions. Cannabis users feel high when the cannabinoids they consume (mainly THC, but also CBD) interact with their body. Cannabinoids produce certain effects by binding to the cannabinoid receptors of the body. There they are then broken down by enzymes. Our cannabinoid receptors have genetic variations from person to person, which in turn can help determine the effects of cannabis, including the duration of the effect.
The main factor in the duration of the cannabis high is the type of cannabis use. We know that the high produced by infused edibles lasts significantly longer. The reason for this is: the length of the high reflects the time it takes for the THC to reach maximum saturation in the bloodstream.
When smoking cannabis, the high sets in almost immediately. THC levels peak within the first 30 minutes to an hour after ingestion. In the case of cannabis-infused edibles, the THC is metabolised by the liver and then enters the bloodstream, taking between 30 minutes and 3 hours to be felt. Depending on the amount of THC consumed and the tolerance in question, a high produced by infused foods can last up to a whole day. Generally, the effect lasts 1-3 hours when taken orally.
When dabbing cannabis concentrates, the effect is immediate. The duration of the effect clearly depends on the individual tolerance and tolerance. Users who regularly consume THC-rich concentrates often experience that the effect wears off within 1-3 hours. Those who have little experience with dabbing can be knocked out for the whole day. Of course, again, one's biological conditions and the cannabinoid and terpene profile of the strain consumed are crucial.
How people experience certain strains and dosages can also change over time, for example if tolerance increases or decreases or something in the body's own chemistry changes. So, as we expected, you can't predict exactly how long the effect will last and it depends on a lot of different factors. But we have been able to give you some rough indications that can help you to estimate it quite well.