How Long Does Cannabis Stay in the Human Body?
Article written by
Tina MagrabiSenior Content Writer
Content reviewed by
Dr. Lewis JasseyMedical Director - Pediatric Medicine
As cannabis is federally illegal, there are many jobs that prohibit its use amongst their employees, even in states with a medical marijuana program Although there are some protections for medical cannabis patients in some states (for example, off-duty use for medical purposes is fine in states like Arizona or Delaware, there are other states where such protections are not in place.
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Although it is possible to detect various kinds of cannabinoids, it is THC and its metabolites that are most often tested for. THC metabolizes into metabolites in the liver. Cannabinoid metabolites are filtered through the kidneys and excreted mostly via urine.
There are three main factors that determine how long cannabinoids stay in the human body. These are:
- How much is used (dosage).
- The ingestion method used (mode of ingestion).
- Regularity of use (frequency).
Age, weight, individual metabolism, levels of physical exertion, and genetics also play a part in how long cannabinoids stay in the system.
As cannabis metabolites are fat-soluble, they bind to fat molecules in the body. This means that cannabinoids stay in the body for quite some time. For heavy users who ingest cannabis multiple times a day, it is possible for THC metabolites to be detected for up to 90 days, usually in the hair and urine.
Here’s a rough breakdown of how long THC and its metabolites can stay in the body.
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Blood Testing for Cannabis
THC and its metabolites are detectable in the blood almost immediately after ingestion or inhalation. For those who have been using large amounts of cannabis regularly, THC metabolites are detectable in the blood for up to one month after last use.
Saliva Testing for Cannabis
Saliva testing is the most common method for roadside testing. For occasional users, cannabinoids are detectable in the saliva for between 1 and 3 days. For heavy users, it is possible to detect THC metabolites for up to 1 month after last use.
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Urine Testing for Cannabis
Urine testing is one of the most common ways of testing for cannabis. Cannabinoid metabolites are detectable in the urine for the following amounts of time after last use:
- Rare or infrequent users (once a week or less): around 1-3 days.
- Occasional users (around three times a week): 3 to 7 days
- Moderate users (four times a week): 5 to 10 days
- Chronic users (daily): 10 to 30 days
- Chronic heavy users (multiple times a day): 30 days +
The urine marijuana test will test positive if the amount of THC in the sample is more than 50 nanograms per milliliter (ng/ml). This is called the cut-off level.
Hair Follicle Testing for Cannabis
Hair testing is the most sensitive and can detect THC metabolites for up to 3 months after last use. Trace amounts of THC’s metabolites can remain in the hair for quite some time. Usually, a 1.5-inch hair segment is asked for in order to provide a window of use over the last three months.
Whilst hair follicle tests can provide some information about a person’s cannabis use, they are not always accurate, and the tests often produce false negatives. Hair samples are also prone to contamination, making them difficult to detect with high degrees of accuracy. Hair follicle testing is usually used in tandem with urine testing.
Is it possible to detect CBD?
Most drug tests searching for cannabis are calibrated to detect THC and its metabolites. Whilst it is certainly possible to test for CBD and other cannabinoid metabolites, it is not common to do so. CBD also has little psychoactive effect, so it is unlikely that CBD is going to be tested for.
Where CBD may produce a positive result for cannabis use is when products with high concentrations of CBD are used regularly. In such instances, it is not the CBD that is being detected, but the building up of trace amounts of THC over time. THC has a tendency to accumulate, even when used in almost minuscule amounts.
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There are also some hemp-derived CBD products that have tested above the 0.3% THC limit, so it is also possible to ingest a CBD product that contains higher levels of THC without realizing it (i.e. it produces almost no psychoactive effect, but ends up being detected and pushes you past the 50 ng/ml THC metabolite threshold. We recommend you carefully read the labels of all products to ensure you are aware of what is included before consuming any medical cannabis product.
Is it possible to flush out cannabinoids from the body?
Cannabinoids are lipophilic, meaning they bind with lipids and fats in the body. This makes it difficult to clear the body of their metabolites. Exercise, a healthy diet, plenty of green tea & water, and herbal & vitamin supplements could potentially help rid the body of cannabinoids and their metabolites, but it will likely take around 1-2 months to get below the threshold for most people who are regular users.
Regardless of the testing method, cannabinoids can be incredibly difficult, if not impossible, to flush out with over-the-counter products touting the ability to beat your upcoming drug test. Time and patience are one’s greatest allies when attempting to rid their body of cannabis metabolites and the only way you can guarantee testing below the 50 ng/ml cut-off level for cannabis metabolites. Hopefully, employees don’t have to hide their cannabis use for much longer as the landscape of cannabis acceptance is growing on the federal level.
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