Driving and Medical Cannabis

Driving with a medical cannabis prescription is legal in the UK; a medical defence may be supported if you are unimpaired and take it as prescribed. The DVLA may need to be notified of medical conditions or medicines that can affect your driving.

A medical cannabis prescription legally obtained in the UK means you can drive so long as you are unimpaired and taking your medication as your prescriber and product guidance directs.

Patients may be able to rely on a statutory medical defence if they are tested for drug driving if they are not impaired.

Key Takeaways

A statutory medical defence may be available to UK patients prescribed medical cannabis, but it is not guaranteed and depends on the circumstances
For this defence to be potentially relevant, the medical cannabis must be prescribed by a specialist, taken as directed, and the driver must not be impaired
Meeting the above criteria does not guarantee the defence will be accepted by the courts.
Patients should carry evidence of their prescription when driving (a Releaf medical cannabis card may help)
The DVLA requires notification of certain medical conditions but not all prescriptions. Consult your specialist
Even with a valid prescription, driving while impaired remains a criminal offence.

At a glance: Driving and medical cannabis UK

Legal status of driving with a medical cannabis prescription	It is legal to drive with a medical cannabis prescription if you are unimpaired and take your medication as prescribed. Driving while impaired by any drug, prescribed or not, is an offence under Section 4 of the Road Traffic Act 1988.
The “over the limit” offence (Section 5A, Road Traffic Act 1988)	It is an offence to drive, attempt to drive, or be in charge of a vehicle with a specified controlled drug in the blood that exceeds the specified limit for that drug.
THC driving limit	The limit for THC is 2 micrograms per litre (µg/L) of blood. Medical cannabis patients may be above this limit even if they are not impaired.
Statutory medical defence (Section 5A (3))	Section 5A (3) is only a defence for being over the limit, it does not provide a defence for impairment under Section 4.
Conditions of the defence	For the defence to be upheld, the medicine must be lawfully prescribed and taken in line with the prescriber’s instructions. Using it outside of those directions, such as taking a higher dose or using different timings, can cause you to lose your defence.
DVLA notification duty	You must notify the DVLA if you have a medical condition that is notifiable and may affect your ability to drive safely, such as epilepsy. You can ask your clinician if you are unsure.
What proof do you need	Carrying proof is not a legal requirement, but it is recommended. Useful items include a copy of your current prescription, clinic or pharmacy contact details, and the medicine in its labelled packaging. Private medical cannabis cards like Releaf’s can help explain your situation at the roadside.

The section 5A drug driving statutory medical defence explained

The Section 5A Road Traffic Act 1988 defence can only be upheld if three conditions are met.

The first condition in Section 5A (3) is that the specified drug has been lawfully prescribed. For medical cannabis patients, this means the medication has been prescribed by a specialist doctor.

The next condition is that the lawfully prescribed medication is taken in accordance with any directions given by the person who prescribed it, as well as any accompanying instructions given by the manufacturer or distributor of the drug.

Lastly, possession of the drug immediately before taking it was not unlawful under section 5 (1) of the Misuse of Drugs Act 1971, in this scenario, the THC in your blood has to come from the product you were prescribed.

As well as meeting these three conditions, you must also be unimpaired for the defence to be upheld.

These rules apply to England, Scotland and Wales.

Impairment is always an offence

The Section 5A defence laid out above never covers impaired driving even if you have a medical cannabis prescription and follow the conditions set out.

Section 4 of the Road Traffic Act 1988 is about how you are actually driving and makes it an offence to drive, attempt to drive, or be in charge of a vehicle while unfit through drink or drugs. "Unfit" means your ability to drive is impaired, and there is no medical defence.

The Section 5A defence only covers being over the 2 µg/L THC limit, not impairment.

The law places the judgment of impairment on the driver; before driving, you must decide whether you are fit to drive.

It is good practice to make that decision with your clinician and discuss how your medicine, dose, and method of use are likely to affect you, how long to wait after a dose before driving, and what side effects are warning signs. Medical cannabis containing THC may impact driving ability as it is psychoactive, and effects include drowsiness, dizziness, impaired judgment, slower reaction times, blurred vision, lack of concentration, and poorer motor control.

The DVLA and your prescription

You must tell the DVLA if you have a notifiable medical condition or disability that could affect your ability to drive. There is no clear guidance from the DVLA specifically for medical cannabis; to find out more, read our blog on the DVLA and prescribed medicines.

Being stopped by police

If you are stopped by the police while driving, you can expect a roadside swab test of the mouth which tests for THC in your system. It is important to remain calm and cooperative if stopped.

Officers can also do a field impairment test which checks your balance, coordination and ability to follow instructions.

If the police believe you are unfit to drive, you can be arrested and given a blood or urine test at the station which measures the amount of THC in your system.

Ensure your medication is in its original packaging and that you have a copy of your prescription ready.

Releaf also offers every patient a medical cannabis card, which can help you access your prescription information and clinic records in one place while can help show the police you have a valid prescription.

Eligible Releaf+ patients can also use Releaf Protect, a legal guidance helpline provided by Irwin Mitchell Solicitors, for practical, situation-specific guidance when their prescription is questioned.

Related glossary terms

CBPMs - a guide to cannabis-based products for medical use.
POMs - a guide to prescription-only medications and how they are obtained.
FP10 - the standard NHS form used to fill out prescriptions for them to be dispensed.

Frequently asked questions about driving and medical cannabis in the UK

Can you drive if you take medical cannabis in the UK?

If you have lawfully been prescribed medical cannabis, you are able to drive in the UK as long as you are unimpaired when driving and taking your medication as instructed. You may have to notify the DVLA if you have a notifiable medical condition, such as epilepsy, for which you are prescribed medical cannabis.

What is the section 5A medical defence for drug driving?

The section 5A medical defence for drug driving is a defence that can only be used for being over the limit from blood-level charges, which is 2 micrograms of THC per litre (µg/L) of blood. The defence does not cover impairment.

Do I need to tell the DVLA about my medical cannabis prescription?

There is no clear guidance on notifying the DVLA of a medical cannabis prescription. You must tell them if you have a notifiable health condition or disability that can affect your driving. Find out more by reading our blog on the DVLA and prescribed medicines.

What is the THC driving limit in the UK and does it apply to patients?

The THC driving limit in the UK is 2 micrograms of THC per litre of blood. Medical cannabis patients may be able to use the Section 5A defence if they are over the limit, so long as they are not impaired. Find out more about how long THC stays in the body by reading our blog on how long cannabis stays in your system.

Do I have to carry proof of my prescription when driving?

There is no legal requirement to carry proof of your medical cannabis prescription, but it is a good idea and is why Releaf offers every patient a medical cannabis card. You can also carry your medicine in its original packaging, which may help make a police stop easier.

What happens if the police stop me while I am driving on prescribed cannabis?

Police can do a roadside stop where they see fit, and may request a mouth swab and checks to see if you are impaired. If they believe you are, you can be arrested and a blood or urine sample test will be taken at the station to measure how much THC is in your system. It’s important to remain calm and cooperative, and inform them that you have a legal prescription.

To find out if you are eligible, try our free medical cannabis eligibility checker, it takes under 2 minutes to fill in.

Our medical cannabis glossary can also help you learn more about terms you may associate with medical cannabis.

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