How long medicinal cannabis stays in the human body depends on a variety of different factors. But it is important for patients to have some idea how long cannabis stays in the system, due to drug policies in many places of employment, and the legalities around driving with medicinal cannabis in the system. 

How does the body process medicinal cannabis?

Medicinal cannabis is processed by the endocannabinoid system (ECS). The endocannabinoid system is a complex system of receptors, enzymes and naturally occurring cannabinoids within the human body. While scientists are still developing a comprehensive understanding of everything that the ECS does, we do know that it plays a significant part in maintaining homeostasis and regulating a number of bodily functions, such as sleep, mood, appetite and pain. 

How long does medicinal cannabis stay in your system?

The duration for which medicinal cannabis remains detectable in a patient depends on a number of components. These relate not only to the specifics of the patient and dosage administered, but also to the method of testing. 

It is important to note that when it comes to testing for the presence of cannabis, it’s the tetrahydrocannabinol (THC) within the cannabis which any method of drug testing will measure and detect. 

Blood

While a blood test is one of the most sensitive ways to detect the presence of cannabis, medicinal cannabis does not stay in the bloodstream for a long time. Typically, the markers for cannabis have a shorter window of detection in a blood sample. This window may depend on how long the patient has been treated with medicinal cannabis, but medicinal cannabis is likely to stay in a patient’s bloodstream for between two and 12 hours after they have ingested it. 

Urine

By contrast, a urine sample might detect the presence of cannabis metabolites for some time after a patient has ingested medicinal cannabis. 

How long the cannabis stays in the urine will depend on how regularly they are ingesting it. Patients new to medicinal cannabis may find it’s only detectable one and a half to four days after ingestion. Patients who have been treated with medicinal cannabis for a longer duration may find it lingers in their system for longer, and appears in a urine sample up to a month after it’s last been ingested. 

Given that employer drugs tests can only detect cannabis usage, rather than medical diagnosis, patients should be advised to disclose a medicinal cannabis prescription to employers confidentially and independently of any drug testing. 

Saliva

In a new patient, who has only recently begun medicinal cannabis treatment, a saliva test may find evidence THC has stayed in your system for 12 to 20 hours after medicinal cannabis has been ingested. For those who have been prescribed medicinal cannabis for longer, how long cannabis can be detected in saliva will depend on how large the dosage and how long they have been taking it. But evidence of THC may be detected for up to 30 hours afterwards. 

Hair

Using hair as a method of determining the presence of medicinal cannabis in a patient’s system is the most long range drug testing, with hair follicle tests able to recognise the presence of cannabis for up to 90 days. 

While it may take 24 hours for a negative result to be determined, all nonnegative results undergo a second test, with confirmation of the presence of medicinal cannabis only occurring after 72 hours. 

What are the factors that can impact system longevity?

There are several variables that can impact the amount of time that a patient’s system retains traces of medicinal cannabis beyond the method of testing. 

Frequency

How often a patient is ingesting medicinal cannabis will affect any drug test they are given, whether it be through saliva, blood, urine or hair. The more frequently a patient is taking medicinal cannabis, in addition to how long they have been taking it for, the longer the traces of the medicinal cannabis will remain in their system. 

Dosage

Similarly, the higher or larger the dosage, the longer it will remain in the system. This is because the effects of THC are cumulative, so the more medicinal cannabis a patient consumes, the higher the test reading will be. 

Administration

The method of ingestion will also impact how long medicinal cannabis remains in your system. The quicker it is absorbed, the more rapidly it is metabolised and processed. This means that sublinguals, such as oils, tinctures or dissolvable tablets, which are absorbed more quickly, will also be processed more quickly. Edibles, which need to be digested before they hit a patient’s bloodstream, will take longer to process, so traces are likely to remain for longer. 

Weight

As a fat soluble compound, THC is stored in a patient’s fat cells. This means that although weight plays a part in the way that a patient processes medicinal cannabis, it’s not necessarily about the numbers on the scale; it’s about how much fat the patient is carrying. Those with higher levels of body fat will process medicinal cannabis  more slowly, which means cannabis will be detected in their system for longer. 

Sex

Usually, female patients have more body fat than their male counterparts. As such, women are likely to metabolise medicinal cannabis more slowly, so it remains in their bodies for longer. Other factors, like a patient’s metabolism, how much exercise they do, and whether or not they’re hydrated can also impact how long cannabis stays in the system. 

Find out more

Healthcare professionals can find out more useful information about medicinal cannabis and its administration by accessing the healthcare professionals portal. If you have any questions about our products, contact us today.