‘You can’t drive straight on drugs’

All drugs (illegal, prescription or over the counter medicine) have the potential to affect driving ability.  Commonly they can affect-

• Perception – this involves the human senses of vision and hearing.  Unless a driver accurately understands what he/she sees, it is impossible to react appropriately.
• Judgement – accurate decisions are based on a driver’s ability to assess and judge a given driving situation.  Poor judgements often result in collisions.
• Coordination – drivers must coordinate hand, eye and foot movements to operate a motor vehicle successfully.  Loss of such ability greatly affects performance.
• Vision – as have been previously stated, vision is the key to information gathering and processing and safe driving.  Visual impairments make it difficult to search, evaluate and execute appropriately.
• Mood – a driver’s mood may cause him/her to take unnecessary risks or be so lethargic as to fail to act correctly in a dangerous situation.

Some illegal drugs present special problems.  Cannabis, for example, can affect reactions and response to what other drivers are doing.  This can have serious consequences – for instance, having to stop suddenly or to respond to the actions of other vehicles or pedestrians.   The ability to concentrate and maintain attention, make decisions and to react to unexpected events is greatly reduced.  Important road signs may be missed.

Some examples of prescription medications that can affect driving are:

• Sleeping tablets
• Muscle relaxants
• Sedatives
• Antihistamines
• Some strong painkillers

If worried about the effect that a medicine has on your driving, stop driving – not the medicine.