Drivers, especially young drivers, need to be aware that medication, whether prescribed or over-the-counter, can impair your ability to operate a vehicle safely. Effects can include reduced ability to divide attention, poor time and space management, and reduced ability to allocate concentration. These effects can increase crash risk by up to 8 times, with some crashes resulting in death (Canadian Centre on Substance Use and Addiction).

Drivers with a medical condition may be more susceptible to the side effects of prescription drugs because they often use multiple medications in combination. Plus, they are more likely to have pre-existing conditions that can increase both the frequency and severity of adverse effects.

Prescription cannabis

Just because a medication was prescribed to you by your doctor does not mean it is okay to drive after use. This includes prescriptions for medical cannabis. Cannabis is an impairing substance and should not be used before driving. Medical cannabis users are not permitted to drive while impaired. Medical users who have consumed cannabis have to make other plans (for example taxi, ride-share, designated driver) to get to their destination.

For more information, see Cannabis and driving.

Prescription drugs that impair driving

While many prescription and over-the-counter drugs do not necessarily affect driving abilities, many of these drugs can have side effects severe enough to impair driving, even at safely prescribed doses. And the effects of some can last for several hours. According to the American Automobile Association, the following drugs have the potential to impair driving:

  • tranquilizers
  • narcotic pain pills
  • sleep medicines
  • some antidepressants
  • cough medicines
  • antihistamines
  • decongestants

Impairment by some drugs, such as sedatives, might not be obvious and the effects of some sleep medications can linger into the next morning.

Effects of prescription drugs

Effects that prescription drugs can have on drivers include:

  • slowed reaction time
  • sleepiness
  • poor psychomotor performance
  • impaired coordination
  • reduced ability to divide attention
  • increased errors
  • difficulty following instructions

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