Unlike some other drugs, THC doesn’t “go away” shortly after its effects wear off. Even if users don’t feel “high,” there’s a significant chance they could have residual THC compounds in their cells. Cannabis consumers must keep this feature of marijuana in mind; a positive THC screening could result in costly repercussions.
So, how long does it take for cannabis to filter out of the body? Unfortunately, scientists can’t give a precise answer. While we know THC is detectable long after ingestion, how long it stays in each user’s system depends on multiple factors.
It may be impossible to give a “one-size-fits-all” answer for THC absorption, but a few recent findings could be of use to MMJ patients and recreational consumers alike.
How Long Will THC Stay In The Body?
The short answer is that delta-9 THC could remain in a person’s body anywhere between a few days to a few months. Unfortunately, it’s impossible to get more specific than that.
A significant reason researchers have a tricky time tracking THC has to do with its metabolites. Interestingly, even if there’s no delta-9 in a person’s body, there could be one of many compounds related to delta-9 THC.
When delta-9 THC goes through a person’s liver, it breaks down into roughly eighty THC metabolites. Many scientists believe these secondary chemicals remain in the body long after delta-9 clears via urine or feces.
Research out of Bangalore suggests delta-9 THC has a half-life of about 1.3 days in occasional users. However, Mayo Clinic scientists believe the metabolite THC-COOH could be found in urine within seven days after smoking a joint.
Not only do delta-9 THC and metabolites remain for a long time, new data suggests it appears in a person’s bloodstream almost immediately. Indeed, the University of Bern reports THC concentrations in blood plasma peak at five minutes post-ingestion.
For extra complexity, all of these THC molecules are fat-soluble. Unlike water-soluble nutrients like B vitamins, THC won’t dissolve in water and quickly pass via the kidneys. Instead, delta-9 and its metabolites will attach to the body’s fat cells. It could take many days for these stored THC molecules to get released and exit the body.
Will A Person’s Average Weekly Weed Usage Affect THC Readings?
Of the many factors that affect THC absorption, average weekly usage is the most significant.
Simply put: The more cannabis a person consumes, the longer THC will stay in their system.
Also, the more weed a person takes, the more likely they will score a positive result on a standard drug screening.
Findings out of the Mayo Clinic suggest THC detection scores range from about three days to 90 days in urine samples after participants smoked cannabis. Those on the low end of this spectrum took cannabis no more than three times per week. People closer to the 90-day extreme took at least two cannabis products per day.
Another test from the University of Bristol examined hair samples from over 130 participants. Scientists organized these groups into three categories: chronic, light, and non-users. After analyzing a 1 cm hair sample from every patient, scientists noticed a correlation between each person’s self-reported cannabis use and the likelihood of a positive result.
Lab technicians found high concentrations of cannabinoids like THC in 75 percent of study participants who used cannabis “chronically.” By contrast, about 40 percent of those in the “light user” category had positive cannabinoid readings in their hair samples.
Could Different Drug Tests Show Different THC Blood Concentration?
While cannabis use frequency plays a significant role in THC absorption, different testing methods could give unique readings on THC percentages.
For instance, scientists at Boston Children’s Hospital recently examined how long different test samples could detect THC. Of the various methods tested, blood and saliva had the shortest detection window of roughly 24 hours after smoking cannabis. Sweat was higher at between 7 – 14 days when using a sweat patch, while urine tests had an average cutoff of 30 days. Lastly, scientists claimed hair samples could detect marijuana use at least 90 days after smoking.
However, other studies suggest cannabis compounds could remain for much longer in saliva samples. For instance, the National Institutes of Health discovered traces of THC in saliva from chronic users after ~ 28 days of using cannabis.
Although we’re still learning how testing methods affect THC readings, it’s clear each method has a unique sensitivity to this cannabinoid. However, every test will detect THC and metabolites for a more extended period the more frequently people use cannabis.
Does Weight Weigh On A THC Screening?
As mentioned above, THC and its metabolites are fat-soluble. Therefore, most of these compounds will settle in fat cells for days and weeks before being released into the bloodstream.
Given THC’s fat-soluble nature, most scientists assume a person’s weight could influence how long THC remains in their body. The more fat cells there are, the more available “space” THC has to latch onto. Therefore, it probably takes more time for people with an above-average BMI to clear THC from their system.
Although there’s no empirical data tying a person’s weight to the time it takes THC to leave, there’s plenty of evidence that suggests THC clings to fat cells. In fact, a study out of St. Olav University Hospital found that physical exercise increases THC and metabolites in a person’s bloodstream.
Since activities like running “burn” fat cells, they speed up the release of stored THC. For this reason, many people seem to have higher THC concentrations in a urine test shortly after a workout. Even if an athlete didn’t take THC for a few days, it’s likely more metabolites are entering their bloodstream after an intense run.
Does CBD Oil Complicate Drug Screenings?
In theory, CBD should help people metabolize THC faster. According to most studies, CBD blocks THC from landing on CB1 receptors, which means any THC in a hemp product should leave the body relatively quickly.
However, scientists believe THC molecules could be stored in fat cells for days or weeks after ingestion—even if you’re taking a CBD-rich product. Please remember that THC breaks down into dozens of metabolites.
So, while drug tests don’t screen for CBD, that doesn’t mean hemp products can’t trigger a positive THC reading. Per US law, full-spectrum hemp derivatives could have as much as ≤ 0.3 percent delta-9 THC. Depending on a person’s metabolism, it’s possible THC metabolites could be detectable for days or weeks after smoking CBD hemp or taking a full-spectrum edible, oil, or tincture.
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It’s scary not knowing how much THC is in your bloodstream. Even if you haven’t taken cannabis for a while, there’s a chance some THC could still be in your system. Since marijuana tests can have significant consequences, cannabis users need to be extra careful about taking this herb.
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