Published: 1 September 2016


Medicines can Impair Driving

This article is more than five years old. Some content may no longer be current.

Prescriber Update 37(3): 45
September 2016

Key Messages

  • It is against the law to drive while impaired.
  • Warn patients taking medicines that may impair their driving ability of potential effects and encourage them to discuss any concerns.
  • Symptoms of impairment include sedation, blurred vision or inability to focus, as well as feeling manic or overconfident.

It is against the law to drive while impaired. The Land Transport Amendment Act 2009 states that it is an offence to drive while impaired and with evidence in the bloodstream of a qualifying drug1. Qualifying drugs include controlled drugs and prescription medicines. Further information on the legislation is available at

Healthcare professionals can assist their patients by informing them of the potential impairing effects of medicines (this includes over-the-counter and pharmacist-only medicines as well as prescription medicines). Medicines with the potential to impair driving ability include some pain relievers, anxiolytics, antidepressants, sleeping aids, antiepileptics, sedating antihistamines, antipsychotics, medicines used in the eyes, cough and cold medicines and some heart medicines2.

Not every medicine within each medicine class will impair driving nor cause impairment in every person. However, patients should be informed of the potential risk. Additionally, it is important for patients to continue treatment as some conditions requiring medical treatment may themselves affect driving ability if left untreated3.

Symptoms of impairment include dizziness, drowsiness, headache, nausea, blurred vision, slowed reactions, inability to focus, being easily confused, slurred speech and feeling manic or overconfident2. Importantly, the patient may not always be aware that they are impaired and impairment may continue the following day (eg, zopiclone and next-day impairment, see the Prescriber Update article for more information

Further guidance to patients could include:2,3

  • not driving until the patient knows how the medicine affects them
  • avoiding driving completely, particularly during treatment of a short-term condition
  • not driving if the patient experiences any symptoms as described above
  • considering alternative options, such as a different medicine or if it can be taken at a different time of day.

Please note that this information is advisory only. Data sheets for individual medicines should be checked for information on possible driving effects. Medicine data sheets are available at

  1. Land Transport Amendment Act 2009. URL: (accessed 11 July 2016).
  2. NZ Transport Agency. Are you safe to drive? URL: (accessed 11 July 2016).
  3. Medicine and Healthcare product Regulatory Agency (MHRA). Drug Safety Update - Drugs and driving: blood concentration limits set for certain drugs. 16 February 2015. URL: (accessed 11 July 2016).
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