Drug testing has been on the rise in the UK in recent years as authorities and employers seek to improve public health and safety in the workplace, on roads, and in the community in general. But for patients who are using prescription medical cannabis products, the prospect of being drug tested can be worrying – particularly as a significant percentage of police officers across the country may still be unaware of the legality of medical cannabis.
In this article, we’re taking a closer look at everything you need to know about drug testing in the UK, from the most common types of tests to your rights as a medical cannabis patient.
When might a drug test be requested?
Drug tests are most commonly requested at the roadside or in the workplace. For example, if a police officer suspects a person is driving under the influence of drugs or alcohol, or if an employer is concerned the behaviour of an employer may be drug-related.
Employers can also request random drug tests from workers in certain jobs; however, written consent must be obtained. Furthermore, while workers cannot be made to take a drug test, failing to comply when an employer has good grounds for testing could result in disciplinary action.
Such circumstances may include working in sectors which are safety critical such as construction, logistics, transportation, and any job which requires the use of heavy machinery. However, screening companies have indicated that drug testing has also become more common in other industries, including retail and healthcare.
Types of drug tests and how they work
Drug testing can involve the testing of blood, breath, saliva urine or hair. The type of test being used will depend on the circumstances. The most common drug test used in the workplace is the urine drug test, while roadside testing usually involves breathalyser tests or saliva tests. Blood, hair, and nail samples can also be used to provide insight into a person’s drug and alcohol use.
Drug tests are designed to detect the metabolites left behind by certain drugs as they are broken down in the body. Some drug tests can also detect the parent compounds of these metabolites depending on the detection window which can vary significantly.
Is medical cannabis detectable by drug tests?
As mentioned above, saliva, urine, blood, and hair samples can be used to determine cannabis use. This includes the use of some legally prescribed cannabis-based medicines.
THC delta-9 is the primary psychoactive compound found in cannabis. It is this compound and its metabolites that drug tests are designed to detect to determine exposure to cannabis. That means that the consumption of any products containing THC – whether sourced illegally or legally through a prescription – can lead to a negative drug test result.
How long is cannabis/THC detectable?
When it comes to different types of drug tests, it is not only the types of detectable compounds that can vary. As we mentioned earlier, detection windows can also vary significantly, ranging from a few hours to many months.
So, how long can each type of test detect cannabis/THC exposure? Let’s run through the different types of drug tests and their detection windows for cannabis.
Breathalyser Drug Testing
Breathalyser tests measure breath alcohol content to gauge a person’s level of alcohol intoxication and can be conducted at the roadside. However, breathalyser tests currently used by police in the UK cannot detect cannabis use.
If police suspect a person may be under the influence of another drug(s), including cannabis, a different type of test will be required to confirm this. The ongoing legalisation of cannabis in North America in recent years has prompted the development of new “cannabis breathalysers”; however, these are not yet being rolled out at scale.
Saliva Drug Testing
Saliva samples provide a more comprehensive insight into potential drug use. For example, roadside screening tests use saliva samples to indicate the presence of cannabis and cocaine. While these tests can confirm the presence of drugs, they are not effective at determining impairment.
Nonetheless, a positive (and even a negative) roadside screening result can lead to an arrest if an officer believes that your driving is impaired by drugs, even if they are legally prescribed medications. This means you can be taken to a police station for further testing.
Saliva drug tests – also called oral drug tests – can detect THC in saliva (levels above 12 ng/ml) for a window of up to 8-12 hours. However, there are a number of factors that can affect this detectability window, such as whether the mouth has been washed or the individual has eaten or drank anything since the time of consumption.
Furthermore, a recent review-based study recently found that roadside saliva tests can produce “false positives” for impairment due to the length of time THC can be detected in the body.
Urine Drug Testing
Urine testing is the most common form of drug testing in the workplace. It may also be used at police stations to determine the presence of prescription and illicit drugs including cannabis, cocaine, opiates, methamphetamine, amphetamines, PCP, benzodiazepine, barbiturates, methadone, tricyclic antidepressants, ecstasy, and oxycodone.
Urine tests are designed to detect the metabolites of THC, namely THC-COOH. This compound is stored in fat cells and released slowly into the bloodstream over time, meaning it can be detected for significantly longer than THC itself.
THC-COOH can typically be detected in urine from 50 ng/ml for around 7-10 days after cannabis consumption; however, this window can vary depending on factors such as frequency and extent of cannabis use, THC potency, and the metabolism of the individual. In cases of chronic cannabis use, it is possible for this window to be extended up to 30 days after consumption.
Hair Drug Testing
Hair analysis can reveal a history of exposure to drugs and their metabolites over a long period. As such, hair samples can provide more detailed insight and help to establish chronic versus occasional drug use. Hair strand tests can also detect parent drug compounds (THC is detectable from 0.1 ng/mg of hair) in addition to their metabolites (THC-COOH is detectable from 0.002 ng/mg of hair).
Hair drug testing has the longest window for the detection of cannabis use, chronicling exposure up to a period of around 12 months. Hair drug testing is less common than saliva and urine testing but may be requested for court and legal matters when proof of abstinence is required.
Blood Drug Testing
Blood testing can also identify both the parent compounds of drugs and their metabolites. In some instances, the metabolite/drug ratio in the blood can even indicate chronic versus single use. However, drug detection windows for blood testing are much shorter than in other tests.
Blood testing is typically able to detect cannabis use for 25 to 48 hours after consumption, but again, this can vary depending on several factors.
Your rights as a medical cannabis patient
All of this can be a little worrying if you are a medical cannabis patient which is why it is so important to be aware of your legal rights. For example, are you exempt from drug driving laws if you medicate with cannabis-based products? Or can you refuse to take a drug test if asked by your employer?
Medical cannabis and roadside drug tests
While impairment from cannabis inhalation is thought to last around four hours, THC and its metabolites can remain in the body for much longer. This can leave medical cannabis patients in a tough situation if they find themselves pulled over by police. However, patients who are not impaired and are following the advice of their prescribers are likely to have a statutory defence to protect them from prosecution.
Nonetheless, the unreliability of drug tests for proving proof of cannabis impairment paired with a lack of police training regarding medical cannabis laws makes for a long and stressful debate.
Learn more about your rights regarding driving in our article ‘Can you drive if you have a medical cannabis prescription?’.
Medical cannabis and workplace drug tests
Some jobs understandably require random drug testing to ensure the safety of both employees and the public. However, this can be a source of significant stress for medical cannabis patients. While for some patients, such as pilots or heavy goods vehicle (HGV) drivers, medical cannabis is not often prescribed due to the safety implications of potential impairment, increased access to medical cannabis means this issue is becoming more commonplace.
As we noted in our recent article ‘Cannabis at work…’, in these situations, it is a good idea to inform your employer of your medical cannabis prescription before you may be required to take a drug test. While this conversation can be difficult, there are legal safeguards in place to ensure patients are able to take their prescribed medications at work – even medical cannabis.
