Medical Cannabis and Your Workplace Rights in the UK

A Common Source of Anxiety for Medical Cannabis Patients

One of the most frequently asked questions from UK medical cannabis patients — and one of the most important — concerns workplace rights. Many patients are understandably concerned about the implications of their prescription for their employment: Can their employer drug test them? Are they obliged to disclose their prescription? Could they be dismissed for using prescribed cannabis?

These are legitimate concerns, and the answers are not always straightforward. This article sets out the key legal principles that apply to medical cannabis patients in UK workplaces.

Is It Legal to Use Your Prescribed Medical Cannabis?

Yes. Medical cannabis prescribed by a GMC-registered specialist doctor is a legal prescription medication in the UK. Possessing and using your prescribed cannabis-based medicinal products is entirely lawful, provided you are using them as directed and in accordance with your prescription.

Do You Have to Tell Your Employer?

There is no general legal obligation to disclose your medical cannabis prescription to your employer. Your medical information is private, and you are not required to volunteer details of your prescriptions unless there is a specific reason to do so.

However, there are circumstances where disclosure may be relevant or required. If your role involves safety-critical activities — such as operating heavy machinery, driving, working at height, or working in healthcare — you may have a contractual or legal obligation to inform your employer of any medication that could affect your ability to perform your duties safely. This is not specific to cannabis; it applies to any medication that may cause impairment.

If your PTSD, chronic pain, or other condition qualifies as a disability under the Equality Act 2010, your employer has a duty to make reasonable adjustments to support you. Disclosing your condition (though not necessarily your specific medication) may be necessary to trigger this duty.

Workplace Drug Testing

Many employers — particularly in safety-critical industries such as transport, construction, and healthcare — conduct workplace drug testing. Standard drug tests typically screen for THC metabolites, which can remain detectable in urine for days to weeks after use, even in patients using prescribed cannabis.

A positive drug test does not automatically mean you will face disciplinary action. If you have a valid prescription, you should inform your employer's occupational health team or HR department. Many employers have policies that distinguish between prescribed medication use and illicit drug use, though this varies significantly by organisation and industry.

It is advisable to carry documentation of your prescription (such as your prescription label and a letter from your prescribing doctor) at all times, and to be prepared to present this if questioned.

Can You Drive After Using Medical Cannabis?

You can legally drive after using prescribed cannabis, but only if you are not impaired. The drug-driving law in England and Wales sets a legal limit for THC in blood of 2 micrograms per litre — a threshold that can be exceeded by patients using prescribed cannabis. However, there is a medical defence available if you are using a prescribed medicine in accordance with your prescription and your driving is not impaired.

In practice, patients are advised to exercise caution. If you feel any cognitive impairment, drowsiness, or altered perception after using your medication, you should not drive. Discuss timing of doses with your prescribing doctor to minimise any impact on your ability to drive safely.

Getting Support from CPGUK

CPGUK provides free guidance to medical cannabis patients navigating workplace and legal questions. If you are concerned about the implications of your prescription for your employment, our team can provide information and help connect you with appropriate legal or occupational health support.