Drugs and driving: blood concentration limits to be set for certain controlled drugs in a new legal offence

The Department for Transport has introduced a new offence of driving with certain controlled drugs above specified limits in the blood; this is likely to come into force on 2 March 2015.

Article date: July 2014

A new offence of driving with certain controlled drugs[1] above specified limits in the blood is expected to come into force on 2 March 2015.[2] These drugs include some prescribed medicines. Anyone found to have any of the drugs above specified limits in their blood will be guilty of an offence, whether their driving was impaired or not. A preliminary, non-specific roadside test may be used to detect if an individual has any of the drugs in their body. To identify the particular drug taken and quantify blood levels, a blood sample will be taken at a police station and sent for forensic analysis.

The legislation provides a statutory “medical defence” for people taking the drugs for medical reasons, if their driving was not impaired. The conditions of the medical defence state that the individual is not guilty of an offence if:

  • the medicine was prescribed, supplied, or sold to treat a medical or dental problem, and
  • it was taken according to the instructions given by the prescriber or the information provided with the medicine.

The individual may need to provide written evidence to satisfy the points above (eg, the tear-off section of a prescription or the medicine’s patient information leaflet).

If the individual’s driving is impaired, they can be found guilty of an offence under the current law, which has no statutory medical defence and will not change.

Drugs included in the new offence that might be used for medicinal purposes:

  • Cannabis (tetrahydrocannabinol, THC)
  • Cocaine
  • Morphine
  • Diamorphine
  • Methadone
  • Ketamine
  • Amphetamine[3]
  • Flunitrazepam[4]
  • Clonazepam
  • Diazepam
  • Lorazepam
  • Oxazepam
  • Temazepam

Although only a few benzodiazepines and opioids are included in the list above, all benzodiazepines and opioids can impair driving ability. The risk of driving impairment is increased if the medicine is taken with alcohol. Warnings on the risks of driving impairment are already in the patient information leaflet.

Advice for healthcare professionals

  • Any condition that requires medicinal treatment may itself pose a risk to driving ability if left untreated. Therefore it is important to advise patients to continue their treatment.

Advice to give to patients taking any medicine:

  • Continue taking your medicine as prescribed
  • Check the leaflet that comes with your medicine for information on how your medicine may affect your driving ability
  • It is against the law to drive if your driving ability is impaired by this medicine
  • Do not drive while taking this medicine until you know how it affects you (especially just after starting or changing the dose of the medicine)
  • Do not drive if you feel sleepy, dizzy, unable to concentrate or make decisions, or if you have blurred or double vision

Further information:

Information leaflet to give to patients (50Kb)

Guidance document from the Department for Transport: https://www.gov.uk/government/collections/drug-driving.

Article citation: Drug Safety Update volume 7 issue 12, July 2014: A1.

[1] Controlled drugs are defined in the Misuse of Drugs Act 1971

[2] Dependent upon the regulations being approved before Parliament is dissolved on 30 March 2015 prior to the General Election of 7 May 2015.

[3] Whilst amphetamine will not be included in the current regulations to go before Parliament in 2014, it is expected to be included later in 2015 once a limit has been agreed

[4] Not currently licensed in the UK

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