Do drugs impair your driving?


Taking drugs will impair driving skills.

Driving whilst under the influence of drugs is extremely dangerous and can affect driving in numerous ways.

Drug drivers can suffer from slower reaction times, erratic and aggressive behaviour, an inability to concentrate properly, nausea, hallucinations, panic attacks, paranoia, tremors (or ‘the shakes’) dizziness and fatigue. In such a condition, it is a bad idea to be behind the wheel of a car, for the driver and their passengers.

During the phase whilst the effects of drugs are wearing off, the taker may feel fatigued, which will affect their concentration whilst driving.


Cannabis users often think they are safer when they are under the influence because they drive slower. However, this also means that the driver avoids tasks that require effort, like over taking. It also distorts perception of time and distance so other vehicles seem closer than they really are.

The specific effects of driving on cannabis are:

  • Slow driving
  • Avoiding driving tasks that require effort
  • Affects ability to control the car safely
  • Increased reaction and decision times
  • Inaccurate judgement of time and distance
  • Inability to maintain headway
  • Poor control of lateral position
  • Impaired sustained vigilance

Cocaine leads to a sense of over confidence and this is reflected in driving style. Users typically perform higher risk, more aggressive manoeuvres at greater speeds, which is obviously dangerous.

The specific effects of driving on cocaine are:

  • Aggressive manoeuvres
  • Speeding
  • Poor control of the vehicle
  • Erratic driving
  • Over-confident, high risk behaviour

The following effects are likely to occur once someone has stopped taking the drug and are related to the fatigue that results from cocaine use:

  • Inattentive driving
  • Distraction and drowsiness
  • Falling asleep at the wheel

Although it’s not a drug that makes people violent, it is extremely dangerous to drive on ecstasy because it results in:

  • Distorted vision
  • Heightened sounds
  • Increased fatigue and tiredness
  • Affected perception and judgement of risks
  • A more aggressive attitude
  • Day-after effects similar to cocaine, leading to distraction, drowsiness and inattentive driving.
Amphetamine (Speed)

Speed is a stimulant which can make you feel more awake and alert. Users may feel more confident. However, it creates a feeling of loss of coordination. It will make people less likely to react on time to potential dangers. The effects can last up to several hours depending on how it was taken, and from person to person.

The specific effects of driving on Speed are:

  • Headaches and dizziness
  • Irregular heartbeat and breathing
  • Irritability, restlessness and anxiety as the effects wear off
  • After an initial alertness, the user can experience sleeping problems, exhaustion and fatigue

LSD severely distorts senses and perceptions creating visual hallucinations and making someone feel detached from reality. Driving after taking LSD is extremely dangerous and the effects can last up to 12 hours. A 'bad trip' can be frightening and you can experience terrifying thoughts and feelings.

The specific effects of driving on LSD are:

  • Hallucinations
  • Confusion and distrust of the user’s own senses
  • Poor coordination and control
  • Tremors and twitching
  • Increased anxiety
  • Flashbacks can also occur in the following weeks and months

Heroin slows reactions, dulls perceptions and affects coordination. Though the user can feel ‘euphoric’ they often feel sleepy and sluggish, which can cause driving accidents. It is widely agreed that someone heavily under the influence of heroin will be unfit to drive. The numbers of drivers found with heroin in their blood after a road traffic fatality are said to be increasing.

The specific effects of driving on heroin are:

  • Distorted perception / lack of coordination
  • Tiredness
  • Nausea and breathing problems
  • Effects can take anything up to 24 hours to reduce

Ketamine is a 'disassociative' anaesthetic. This means it causes a sense of being separated from the world around you, as well as sedating you and dulling pain like a normal anaesthetic. Ketamine cannot kill you from overdose in the way other drugs like heroin can but it has been implicated in an increasing number of accidental deaths, such as drowning or falling from buildings, because users are simply not aware of what is going on around them.

The specific effects of driving on ketamine are:

  • Distorted perceptions and hallucinations
  • At higher doses - becoming completely unresponsive to the outside world
  • Impaired coordination
  • Drastically slowed reaction times
Gamma Hydroxybutyrate (GHB)

Depending on the dose, GHB acts as both a sedative and a stimulant, with the effects lasting for several hours. At low doses, GHB can cause euphoria and increased sociability. At higher doses, GHB can cause rapid loss of consciousness and other side effects. GHB impairs motor coordination and mental alertness, leading to the inability to concentrate, judge speed or distance and drive in a straight line. The police can easily spot those signs. As such, driving while under the influence of GHB significantly increases the likelihood of road accidents and hospitalisation.

The specific effects of driving on GHB are:

  • Rapid loss of consciousness and sudden sleepiness
  • Vomiting, amnesia, respiratory depression and visual disturbances
  • Slurred speech, jerky body movements, dilated pupils, spitting, lack of balance
  • Inability to focus leading to erratic driving.
Using more than one drug

People often take more than one drug or mix drugs with alcohol. For example, a stimulant like cocaine to ‘sharpen up’ after having alcohol or cannabis. In fact, combining drugs can have a dramatic and unpredictable effect on a user's state and driving.