Drug-driving and prescription medication

Some patients may have questions about licensed medications and driving.

The offence of drug-driving was created by an amendment to the Road Traffic Act 1988 and required separate regulations to be passed in Scotland, as well as in England and Wales.

Guidance has been published for healthcare professionals in England and Wales and Scotland to help them explain the law to patients taking these medicines. The law allows for a 'medical defence' for people who have been prescribed medications, and are taking them in accordance with the prescriber's advice.

As well as giving standard advice about the risks of medicines, such as drowsiness, you may find patients approach you with questions about the impact of their medications on their ability to drive, and whether they might be prosecuted if stopped and investigated by the police. Patients might also ask you for written confirmation of prescribing advice in case they are stopped or after being stopped.

Which medications are included in the regulations?

There are two groups. The first consists of common recreational drugs and the specified limits for these have been set at a low level. They include cannabis, cocaine, MDMA, LSD, ketamine, heroin/diamorphine metabolite and methylamphetamine.

The second group are mainly licensed medications, for which higher limits are acceptable. They include benzodiazepines (clonazepam, oxazepam, diazepam, lorazepam, temazepam), methadone, morphine and amphetamine.

How will drug tests be carried out?

It's already an offence to drive while impaired by drugs under a section of the Road Traffic Act. This is the case regardless of whether or not the medications are prescribed, and this offence remains in force alongside the drug-driving offence.

If police suspect a driver's fitness to drive may be impaired due to drugs, they can stop and screen them at the roadside for the presence of drugs in their saliva. If the test is positive, drivers may then face blood tests to identify whether their blood level of the drug is above the legal limit.

Who has set the limits, and will this mean patients taking the specified medications cannot drive?

The limits have been set by the government in conjunction with scientists and medical experts. It is anticipated that the vast majority of patients taking therapeutic doses of prescribed medication should not have blood levels over the specified limit for these medications.

When will patients be able to claim a medical defence?

If a patient is stopped and investigated by the police for drug-driving, they can raise a medical defence if they are taking the medication for therapeutic purposes, and in accordance with the prescriber or supplier's advice and any accompanying instructions included in the medication pack.

However, the police could still prosecute a driver under existing road traffic offences for driving while impaired due to drugs, for which there is no medical defence available.

What should I consider when prescribing medications on the list?

The legislation shouldn't affect the way you prescribe the medications in question. You will already be advising patients about the risks and side effects of medications.

The MDU advises that you clearly document advice you give to patients about their medications. This is in line with GMC advice requiring doctors to keep accurate and contemporaneous records which should include "the information shared with patients" ('Good medical practice' (2024), para 70c).

You may want to take particular care to record the advice about driving while taking medication, including any written advice, and other factors that may impact on the patient's fitness to drive, such as drinking alcohol.

What should I do if a patient seeks a report for their medical defence?

Patients may ask for a report if they are stopped, tested and found to have exceeded the specified limit for a medication. Some may also request a report as evidence they are prescribed the medication, to keep with them in case they're stopped.

If you're providing a report, bear in mind your duty of confidentiality and disclose only the minimum amount of information necessary for the purpose.

Should I monitor prescribing of these drugs more carefully?

Not necessarily, although you may decide to audit the records of patients on the relevant medications to see if advice on driving while taking the medications is already being documented.

If you become aware that patients might be taking more of their medication than is being prescribed - for example, if a patient is requesting repeat prescriptions too frequently - it would be advisable to discuss the issue of fitness to drive with the patient, ensuring this discussion is carefully documented.

This page was correct at publication on 30/01/2024. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.

Catriona James, Medico-legal adviser

by Dr Catriona James Medico-legal adviser

Catriona graduated from Glasgow University and trained as a GP in the West of Scotland, before joining the MDU in 2001. Since that time she has completed an LLM in the Legal Aspects of Medical Practice and become a foundation member of the Faculty of Forensic and Legal Medicine. Catriona is based in Glasgow.


Login to comment



Report comment

Dr Nicola Lennard, MDU medico-legal adviser

Patients are usually routinely advised not to drive for at least 6 hours after day case surgery (nor operate heavy machinery). The primary concern is that patient's pain is adequately controlled following surgery(to allow mobilisation and aid recovery) and therefore post-operative analgesia should continue to be prescribed in line with the normal therapeutic dose range. It is anticipated that patients taking therapeutic doses of prescribed medication should not be over the specified limit for the drugs. However we advise that you clearly document advice you give to patients about their medications.

Report comment