Patients often have questions about the rules around driving while taking medical cannabis. Having a prescription doesn’t disqualify you from driving, but as with any medication it’s important to follow guidance and understand your rights to ensure you do so safely.
We’ve put together this guide to help you find everything you need to know about driving while on medical cannabis in the UK.
Who is responsible for driving laws and regulations in the UK?
The Driver and Vehicle Licensing Agency (DVLA) is responsible for the safety and regulation of drivers and vehicles in Great Britain. Its main responsibility is maintaining the registration and licensing of drivers and vehicles including the recording driver endorsements, disqualifications, and medical conditions.
The police also play an important role in enforcing driving laws. As well as investigating accidents, they can issue fixed penalty notices for things like speeding, conduct vehicle checks and carry out roadside drug and alcohol testing.
What does the law say about medical cannabis and driving?
Since the law change allowing medical cannabis to be prescribed in 2018, the DVLA has not issued any specific guidance on CBPMs. However, there are strict laws around driving while taking illegal and prescription drugs.
In England, Scotland and Wales it is illegal to drive with legal drugs (prescription or over-the-counter) in your body if it impairs your driving. It’s also an offence to drive if you have over the specified limits of certain drugs in your blood and you have not been prescribed them.
It is recommended you talk to your doctor about whether it is safe to drive if you are prescribed certain controlled drugs such as morphine, opioids and diazepam. As with all other medicines, clinicians should give their patients advice on driving when prescribing CBPMs.
How might medical cannabis affect my driving?
Medical cannabis affects everyone differently so it’s important to be aware of how your medication impacts you before you drive.
CBD alone is not generally thought to have an impact on driving ability. Impairment is usually caused by THC (the main psychoactive compound in cannabis).
Evidence suggests that impairment from medical cannabis containing THC usually lasts for around four hours or less, but this may vary due to factors such as the amount of THC which has been consumed, individual tolerance, metabolism and whether it has been taken on an empty stomach.
Some of the common side-effects of THC which may affect driving ability include:
- Drowsiness,
- Impaired judgement
- Slower reaction time
- Poorer control of motor skills
- Lack of concentration
- Confusion
- Blurred vision
The law expects drivers to be aware of how their medication affects them. If you feel any of these effects, or are otherwise impaired after taking medical cannabis, you should not drive.
What are the risks of driving after taking medical cannabis?
According to a 2022 report by the Department for Transport, data suggests a “low-to-moderate increase in crash risk” when driving on cannabis, compared to driving sober. However, medical cannabis users likely “pose less of a risk” than those consuming cannabis recreationally.
How do I know if I’m safe to drive while on medical cannabis?
It is generally safe to possess and take your medicine and continue to drive a motor vehicle, as long as the following requirements are met:
- You are not impaired
- The medication has been prescribed by a specialist consultant, and you can provide evidence of this
- You are following the instructions provided by your consultant, as well as the manufacturer or distributor of the medicine.
You should be especially cautious when starting medical cannabis treatment and after increasing the dose, until you know how it will affect you. Your consultant should inform you of possible interactions of CBPMs with other medications.
According to the DVLA, the elements required for safe driving include: attention and concentration, good reaction time and coordination. You should not drive if you feel your ability to drive safely is impaired.
Do I need to tell the DVLA about my prescription?
UK law requires that drivers tell the DVLA about any medical condition that could potentially affect their driving. There is an online service to help you check if your condition needs to be reported.
There is no specific guidance which states that you must inform the DVLA of the fact you have a medical cannabis prescription, unless it is related to a condition which could affect your driving. However, everyone’s circumstances are different, and you should speak to your prescribing doctor for further advice. If you are taking certain drugs which could affect your ability to drive you may need to declare these.
Patients must also inform DVLA and give up their licences if their doctor tells them to stop driving for three months or more, or a medical condition affects their ability to drive safely for the same period.
What is the legal limit for driving while on medical cannabis?
In the UK, the legal limit for THC while driving is 2 micrograms per litre (μg/L) of blood. However, THC can be detected in the blood long after any acute effects or impairment has worn off, sometimes up to several weeks.
Legislation has not been amended to account for patients who may be using CBPMs on prescription. This, and the lack of awareness of their legality, has resulted in patients being arrested despite not being impaired at the time of driving.
What happens if I get stopped by the police while driving?
Under the Road Traffic Act, police can stop any driver if they have reason for concern and request that they take a roadside drug test (oral swabs). If THC is identified you may be arrested and required to take a blood test to determine the levels in your system.
However, if you have a legal prescription for medical cannabis and are following the guidance of your prescribing doctor, you will have a statutory ‘medical defence’ in court should any charges be brought.
If you find yourself in this situation, try to stay calm and explain, showing the officer a copy of your prescription.
If the blood test shows THC levels above the legal limit and you cannot prove a valid medical defence, you could face a driving ban, a fine, or imprisonment.
What information do I need to verify my prescription?
If travelling with your medication you should always ensure it is in its original packaging and that you have a copy of your current prescription to hand.
If my job involves driving, can I continue to work with a medical cannabis prescription?
If your job involves driving or operating heavy machinery, you may need to inform your employer, the DVLA and your insurance company about your prescription to ensure you can continue to do your job safely. You should discuss this with your prescribing doctor.
Employers have a legal duty to ensure the health, safety, and welfare of both their employees and anyone affected by the employer’s undertaking. This includes assessing the risks associated with the use of prescription medicine in the workplace.
It is your responsibility to inform them of your medical cannabis prescription so they can carry out a thorough risk assessment and can make reasonable adjustments where necessary.
Under the Equality Act employers have a legal obligation to make reasonable adjustments for an employee who is disabled in certain circumstances, which may include the use of prescribed medicines at work.
Where can I get further help?
If you have concerns or questions about driving while taking medical cannabis you should speak to your prescribing doctor.
The Cannabis Industry Council has published more detailed guidance on driving with a medical cannabis prescription here.
CannCare is an organisation which provides support for medical cannabis patients who have encountered issues with police and other public bodies.
You can also contact anna’s patient support team directly here.