NHS Greater Glasgow & Clyde Area Drug and Therapeutics Committee
Greater Glasgow and Clyde Medicines
Medicines Update

Controlled Drugs and Patients' Ability to Drive

The Department for Transport has introduced a new offence of driving with certain controlled drugs (CDs) above specified limits in the blood; this legislation came into force in England and Wales on 2 March 2015. Information from Police Scotland is that this legislation will not apply to Scotland, however it remains an offence to drive while impaired by drugs and will affect anyone crossing the border.


When prescribing or reviewing any medicine for patients who drive, consider that the ability to drive can be affected by drowsiness and / or cognitive impairment caused by certain CDs and other medicines such as antidepressants, antipsychotics, antiepileptics or antihistamines.  Other side effects such as blurred vision, dizziness or nausea may also impair ability to drive and patients should be suitably educated.  The risks may be greatest soon after initiation and after dose increases. In general, it is good practice to consider reducing medicines to minimum effective doses or reduce and stop if appropriate. Warnings on the risks of driving impairment are already in the patient information leaflet. Advise patients to continue taking their medicines as prescribed but not to drive if they feel their ability has been impaired by prescribed, OTC or other drugs or by any illness / medical condition.   The DVLA medical standards on fitness to drive can be found here.


Controlled drug


















Lysergic Acid Diethylamide

















In England and Wales, drivers with any of these drugs in their blood above the specified limits will be guilty of an offence, whether their driving was impaired or not. However, there is a medical defence for people taking the drugs for medical reasons in accordance with the prescriber’s or manufacturer’s directions, as long as their ability to drive was not impaired.