Medical Cannabis at Work: What Should UK Employers Do?

What do you do when an employee tells you they take prescribed medical cannabis? Do you stop them working, arrange a drug test or change their duties?

This is an issue we are encountering more and more often and the way you manage it isn't as difficult as you may think.

Let's break this down.

First off, start off by conducting a medical risk assessment (There is a step by step guide on how to do this, to download for free, on The Bainbridge Institute). Remember that a prescription does not automatically make someone unsafe, and it does not automatically mean they are fit for every task.

At First Cohort, our approach to medical cannabis in the workplace is clear: understand the medication, assess the person’s duties while they are taking the medication and manage the actual risk.

Check the prescription and understand the test

Ask to see a current, in-date prescription issued in the employee’s own name. Check that it matches the medication they declare, handling this information confidentially and in line with GDPR guidelines.

Medical cannabis containing THC can, and more often will, produce a positive workplace drug test. However, that result alone does not establish whether someone was impaired while working.

The result is information. What you do next matters.

If you feel that you need to conduct a Point Of Collection test, remember that this type of test is a screening result, not a final conclusion. Should a non negative result be recorded you should follow the appropriate laboratory confirmation process and have the result professionally reviewed alongside the declared prescription (a lot of labs do this). This helps establish what has been detected and whether the medication could explain it.

The question for your business is then: can this person carry out their duties safely? A laboratory result alone cannot answer that.

What if the test is negative? Do not immediately assume the employee has been dishonest about taking their medication. The product, dose, time since use and type of test can affect detection. The substance may be below the test’s cut-off level, or the test may not cover it.

A negative test is not a fitness-for-work certificate, just as a positive result is not proof of impairment.

Make the assessment useful for the job

You need a clear decision about the work the employee actually does. Can they operate machinery safely? Does their role involve driving, working at height or responsibility for others? Have they reported side effects, or have you observed changes in their performance?

Use your medical cannabis risk assessment to identify the risks, decide what controls or temporary adjustments are needed and record the reasons. Where needed, you should consider seeking expert advice. Review the assessment when any changes to work practises are in place, or when medication, duties or circumstances change; do not advise employees to stop prescribed treatment.

If someone appears impaired, take them away from their work station and make both them and the situation safe immediately. Do not allow them to drive elsewhere for a test. A negative screening result should not override a genuine safety concern.

Give your managers a process they can follow

Your workplace drug and alcohol policy should help a manager handle this conversation confidently. It needs to explain medication disclosure, assessment, testing, confidentiality and the next steps when a concern arises.

A policy that simply says “positive test equals dismissal” leaves important questions unanswered and potentially leaves your company open for tribunal claims. So does accepting a prescription without assessing the risks.

At First Cohort, we help businesses turn these situations into clear, practical decisions through policy reviews, workplace testing, manager training and support. We help you understand the result, assess the risk and establish a suitable way forward.

“Failure shouldn’t mean fire.” It should mean taking the right next step, based on evidence and circumstances, with safety at the centre.

Would your managers know what to do if an employee disclosed medical cannabis use tomorrow? Speak to First Cohort and put a clear process in place.