Not all drugs impair driving ability, but there are many different types that can. According to the National Highway Traffic Safety Administration, substances that can cause impairment include illicit drugs, such as cannabis, methamphetamine and cocaine, as well as those that a driver can obtain legally, such as prescription and over-the-counter medications.
These various substances can affect the body in many different ways. Though the effects are different, all can negatively impact driving ability.
According to AAA, cannabis is a collective term that includes marijuana, its derivatives and related synthetics. Depending on the method of administration, the effects of cannabis can last from two to three hours. During that time, it diminishes coordination, reaction time, attention, psychomotor function and virtually every other capacity necessary for driving.
Medications include substances available over the counter to treat a medical condition as well as those available with a prescription from a doctor. Both prescription and over-the-counter medications may cause side effects that interfere with driving ability, such as drowsiness. Patients should carefully read and closely follow any instructions for taking the medication, especially warnings against operating heavy machinery such as a car.
Illicit stimulants include cocaine and methamphetamine. While drugs such as cannabis may slow down the central nervous system, stimulants cause it to speed up. Depending on the substance, the effects can last between five to 12 hours. During this time, a driver who has used stimulants may become more reckless behind the wheel. Increased irritability from stimulant use may lead to aggressive driving behaviors. A driver who has taken stimulants may experience exaggerated reflexes.