How long does marijuana stay in your system?

Even though medicinal cannabis has been legalised in Australia for a few years, there are still certain laws which may not exactly align with a patient's best interests.

Some workplaces conduct regular drug testings, and may or may not consider any valid prescriptions you possess. The other main concern for Australians is the implications of driving after consuming cannabis. Whilst there are currently no tests which can accurately determine cannabis impairment, there are some which are able to detect traces of THC in your system.

Having any amount of THC in your body whilst driving is still illegal in Australia, whether or not you carry a valid medical prescription.

In this article, we explore the factors which can influence how long cannabis can linger in your system, and the different types of tests that are used to screen for THC.

How long does marijuana stay in your system?

Our bodies process cannabis in the same way they do pharmaceuticals and supplements. Oftentimes, the medicines we ingest are in an inactive chemical form.

Metabolisation by our bodies creates a version of the chemical that is more active than the initial compound and easier to eliminate. These factors are how doctors take into consideration when deciding on what types of medication to prescribe to you, or figuring out the correct dosage.

Just like other medications, cannabis stays in our bodies long after the effects have worn off. As each of our bodies differs in physiology and genetic variants, there is no way to predict exactly how long your body stores cannabinoids. But as a general guide, cannabis can be detected in the system for up to 90 days after use, depending on the type of drug test conducted and other factors.

What are cannabinoids & how long do they stay in the body?

The cannabis plant contains more than a hundred cannabinoids, each of which holds its own potential therapeutic properties. Of all these cannabis compounds, Cannabidiol (CBD) and Tetrahydrocannabinol (THC) are by far the most well-known.

Some may be surprised to discover that the human body produces its own cannabinoids, called endocannabinoids. These exist as a part of our largely unexplored Endocannabinoid System (ECS). This system is very important and acts as an internal regulator for biological processes that dictate our mood, perception of pain, stress levels, and immune system.

CBD and THC are very different in many ways, including how long they are metabolised in the body.

CBD in the body

Drug tests that look for cannabinoids are set up to identify traces of THC, so CBD isolates and Broad-Spectrum CBD products will generally not produce positive results.

Note: Although Broad-Spectrum CBD products only contain trace amounts of THC, frequent enough use might cause you to test positive in a drug test.

THC in the body

While THC is a psychoactive cannabinoid, it also has therapeutic value.

For reasons still under research, THC as a cannabinoid is more potent than CBD and as we will explain below, is more likely to be stored in our body than CBD. This is especially true in the case of large doses of cannabis and high concentrations of THC, which take a lot longer to leave the body.

How long does cannabis stay in the body?

"It’s always important to consider how much cannabis you are consuming before determining how long trace amounts will be present in your body"

The detection window for cannabis in our systems depends on what is being tested. Cannabinoids can be found in your saliva, blood, urine, and even your hair. Each of these has its own rates for metabolisation and timeframe which they can be detected.

The rates listed below are based on less-frequent users. It’s always important to consider how much cannabis you are consuming before determining how long trace amounts will be present in your body.

How long does THC stay in blood?

When cannabinoids undergo metabolic transformation they become by-products, which are different from the chemical forms we ingested. These by-products are known as metabolites and are what most drug-tests look for in order to identify cannabis use. The blood tests can usually detect these metabolites 1 to 2 days after use[1], however, the detection window may be extended up to a week [2] depending on the frequency of cannabis use.

How long does THC stay in urine?

Urine testing is one of the most common methods of drug and toxicity due to the fact the majority of metabolic byproducts are eliminated in this way. These types of tests also look for THC metabolites.

Depending on your type of use, it will take 3 days to a few weeks to be expelled by your system.

In the case of more frequent, long-term users, THC metabolites may be present in your body even after a month[3]. This is due to an accumulation of cannabinoids in the body’s tissues which cannot all be expelled at once.

How long does THC stay in saliva?

Testing oral fluid is one of the more effective ways to detect recent cannabis use. For this reason, roadside sobriety tests frequently make use of this method, using its simplicity and difficulty to cheat on.

THC is generally detectable in your saliva for up to 48 hours for regular users. If you are a heavy user however, THC can sometimes still be found in the saliva even after 72 hours[4]. One study conducted in 2014 suggested THC was still detectable for some users up to 8 days[5].

How long does THC stay in hair?

Did you know that your hair doubles as a sort of biological record that keeps track of the most notable vitamins and minerals present in our systems? Due to the nature of our bodies’ distribution of cannabinoids into the cells of our scalp, THC is traceable in hair samples for cannabis users.

Hair testing has the longest detectable timeframe for cannabis, which is able to find traces of cannabis for up to 90 days[6]. In most hair drug tests, samples are taken from 3-4cm from the scalp. As hair generally grows at around 1cm per month, it means the hair sample can detect drug use up to 90 days prior.

Analysis of samples past the 3 month period may no longer be accurate due to the dilution of the cannabinoids that may be present in the hair.

Which factors influence how long cannabis stays in our bodies

As with other types of medication, individual responses to cannabis compounds can vary depending on multiple personal factors. Genetics, gender, and physiology can all enhance or hinder someone’s experience with cannabis. As well as the body’s metabolic response to the compound.

For those who are more sensitive to cannabinoids, it is possible that they will linger in your system for longer than periods of time than those who are less sensitive.

Frequency of use

As cannabinoids build up in bodily tissues over time, the more we ingest cannabinoids, the higher concentrations exist in our bodies’ stores. This means more time is needed to metabolise and excrete the deposits of THC metabolites.

THC concentrations and dosage

Similarly, the more concentrated the dose of cannabis, the more metabolites will be stored, and so it takes longer to eliminate them from body tissue.

Method of use

As previously mentioned, the different ways to consume THC and CBD vary depending on application method and personal preference. Where inhaling cannabinoids results in a quick uptake, the concentration of cannabinoids and the amount you smoke will impact how much of the compounds are metabolised and excreted, or stored.

How long does it take to feel marijuana’s effect & how long does it last?

This depends on a few factors surrounding your personal usage of cannabis products. Most significantly, the application method (ingesting, inhaling, or topical application) will directly contribute to the intensity and duration of the cannabinoids’ effects.

Generally speaking, inhaling cannabinoids through methods such as smoking, vaping, or dabbing results in a much more efficient uptake of compounds. Creating a near-instant effect.

Conversely, when CBD or THC is eaten or taken under the tongue, it follows the process of digestion which takes a lot longer to metabolise the cannabinoids. This is a much more effective process, resulting in a stronger and long-lasting effect.

How is cannabis metabolised by the body?

Drug metabolisation is the body’s natural process of restructuring medicines and supplements from their initial compounds, into those which can be eliminated by our bodies.

Once cannabinoids are consumed, they are circulated in the bloodstream which transports those compounds through the body and into the liver.

Metabolic enzymes are present all over the body. However because the highest concentration of metabolic enzymes is found in the liver, this is where most of the action takes place.

Although the metabolisation of CBD and THC follows the same process, CBD does not undergo as much chemical alteration. As it is largely unchanged when it is eventually eliminated fewer metabolites are left in the body, and so are easier to eliminate.

How long does THC take to metabolise?

Once metabolised, THC becomes a version of the original compound that is more active in the body called 11-OH-THC which is responsible for producing the compound's desired effects[7].

After being transported around the body in the bloodstream for the second time, this THC metabolite is brought back to the liver. Where it is converted into an inactive compound named THC-COOH.

Unlike its precursor, THC-COOH does not bind to cannabinoid receptors, and therefore does not produce any effect.

When there is an excess of 11-OH-THC in our bloodstream, these lipid-based molecules bind with fat cells throughout our bodies and can be stored there for extended periods of time. These active forms of THC metabolites may be released back into the blood when fat is used by the body.

This will not, however, result in a second round of effects, as the levels at which metabolites are released are nowhere near the levels following ingestion. That being said, while these metabolites might not have a noticeable effect, they will be metabolised by your body and result in testing positive for a drug test.

Can you predict how long cannabis will stay in your system?

Cannabis and its therapeutic constituents are still largely undiscovered in modern medicine. What information we can confirm is generally applicable, but will vary interpersonally.

"Your frequency of cannabis use, genetic factors and personal sensitivity to cannabis can all impact how long cannabis remains detectable in your system"

If you’re worried about the possibility of being tested, remember that there are several factors which might inhibit your body’s ability to expel cannabis metabolites from your body. Your frequency of cannabis use, genetic factors and personal sensitivity to cannabis can all impact how long cannabis remains detectable in your system.

Ultimately there is no accurate way of determining if trace amounts of THC still exist in your body, aside from testing. The rough window of detection outlined in this article should give you an idea of different timeframes that are most likely to result in a positive drug test. If in doubt, speak to a medical professional in regards to your driving and drug testing requirements prior to consuming cannabis products.