The content provided on this blog is intended for educational purposes only and should not be construed as medical advice. We strongly advise readers to seek guidance from a qualified healthcare professional regarding any medical concerns.

To reflect its medicinal nature rather than recreational use, we prefer the term ‘medical cannabis’ over terms such as ‘marijuana’, “grass”. or ‘dope’ which may carry negative connotations.

The opinions expressed in the blog belong to the respective authors, who are not medical professionals, and may not necessarily align with those of Lyphe Clinic. Lyphe Clinic does not endorse any specific products or services mentioned, except those provided through Lyphe Clinic.

Readers should be aware that the legality of medical cannabis varies by location, and this disclaimer may be subject to periodic updates.

As the number of medical cannabis patients continues to grow, it is important to keep informed on the latest guidance when driving with a prescription. 

Am I eligible for medical cannabis?Check eligibility

What does the law say about driving with a medical cannabis prescription? What risks do drivers face? Do drivers have a responsibility to inform the DVLA? What should patients do if stopped by the police? This post aims to answer these questions and offer some clarity to patients. 

The Law

UK law currently states that it is illegal to drive if you are unfit to do so following the consumption of legal or illegal drugs.

Guidance from the DVLA states that patients should be “free from any medication effects that would impair driving”. Medical cannabis is standardised to specific quantities of cannabinoids, which include tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD does not usually cause significant drowsiness or impaired cognitive function. THC is often associated with drowsiness, impaired coordination, and tiredness. If you are affected by any medical product that you have used, you must not drive or operate machinery.  

The law at the time this leaflet was written, states that a patient must not have 2 micrograms or more of THC in each litre of blood. This amount of THC may be present with little medical cannabis use. The amount of THC in your blood can remain at a level that is greater than the legal limit to drive for several days or even weeks after using medical cannabis. Patients will often not experience side effects, even though the amount of THC in their blood exceeds the legal driving limit.  

Patients taking any medicine that causes impairment must not drive if impaired as this is an offence. Patients taking medical cannabis should inform the DVLA/HGV of the medicine(s) that they are taking as well as any relevant conditions that may affect their ability to drive. Further information is available here: https://www.gov.uk/health-conditions-and-driving  

Recent research suggests that impairment from medical cannabis can last for 4 hours or less when vaped and longer when orally ingested. This is down to the individual driver to judge whether their ability to drive safely is impaired, as with any other prescribed medication.  

If a driver is deemed to be too impaired whilst driving and is convicted of a drug driving offence they could face: 

  • A minimum 1 year driving ban
  • Unlimited fine
  • Up to 6 months in prison
  • A criminal record

Should I tell the DVLA about my prescription? 

Under UK law, drivers must inform the DVLA if they develop a ‘notifiable’ medical condition or disability that affects their ability to drive safely. Of the notifiable conditions, the only one commonly treated with medical cannabis is epilepsy. Therefore, only patients with medical cannabis prescriptions to treat epilepsy have a mandatory duty to inform the DVLA. 

All other patients are strongly advised to inform DVLA of their prescription as a necessary precaution, as Cannabis Based Medical Products, do have a variety of side effects, that can impair driving. This can also support with avoiding risk of losing your licence in the case of a collision, and to comply with the law. We also strongly advise anyone who drives to and from work and/or for work, to update their employer, as they can support you with an Occupational Health referral.  

Drivers must also surrender their licence to the DVLA if their doctor tells them to stop driving for 3 months or more, or if their medical condition affects their ability to drive safely for this same time period.  

All HGV drivers are obliged by law to notify your organisation of your prescription. Please follow your internal company guidance on reporting.  

What should I do if I get stopped by the police?

The law currently states that drivers stopped by the police will have to undertake a roadside drug test which screens for the presence of illicit substances, including cannabis. If this returns a positive result, the individual will then have to take a urine or blood test at a police station, which is enough to secure a conviction. These tests have been criticised as they test for presence rather than impairment, meaning anyone who has consumed cannabis in the past few days may be over the limit, putting them at risk of prosecution.  

Despite this, patients who are being prescribed Cannabis Based Medical Products and are following the advice of the prescriber, clinic and the law, would be protected under the medical defence category. This category only applies to patient’s who use their medications as prescribed and are not impaired when driving, which is illegal.  

To alleviate the stress of being pulled over, the Seed Our Future Campaign has published a ‘Statement of Fact’ document that drivers can provide to the police which sets out the statutory defence. Drivers with medical cannabis prescriptions are advised to print this out and keep this in their car. If pulled over by the police, drivers should present the document to the officer, alongside a copy of their prescription and ask the officer to politely carry out their due diligence. Providing patients supply this evidence of a legal prescription, there is no reason for police to escalate things further by taking a swab or blood test. 

If you require any supporting documentation from the clinic regarding your prescription, please log into your patient profile and download the following letter titled: Legality of Medicinal Cannabis UK or alternatively email the clinic at info@lyphe.com and request the letter to be emailed to you.  

Take Home Messages

The key points for drivers with medical cannabis prescriptions are as follows:  

  • Patients should not drive if impaired 
  • Drivers only have a mandatory duty to inform the DVLA of their prescription if it is used to treat epilepsy. With that said, we strongly advise all drivers with a prescription should notify the agency to avoid losing their license should they get into a collision 
  • All HGV drivers must report their prescription  
  • Drivers with medical cannabis prescriptions have a medical statutory defence 

Related Insights

Whilst you’re here you might also like to read…