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The Impacts of Substance Use on Driving

On Behalf of | Jan 10, 2023 | Auto Safety, Personal Injury Law

Driving under the influence of drugs or alcohol can be dangerous for you and other drivers on the road. Different substances can impair a driver’s ability to make sound decisions, recognize potential hazards in traffic, and react to environmental changes. This blog post will discuss how various substances impact your driving.


Alcohol is one of the most common substances used before driving. It has the ability to reduce reaction time, decrease coordination, and impair judgment while driving. A survey conducted by National Highway Traffic Safety Administration (NHTSA) reported that 32 people die every day in motor vehicle accidents involving an impaired driver with a blood alcohol concentration (BAC) of over 0.08%. In fact, approximately 30% of all traffic fatalities involved at least one drunk driver.

According to the NHTSA, the following effects of BAC are predictable for drivers:

  • 0.02 – decline in visual functions and ability to multitask.
  • 0.05 – reduced coordination, ability to track objects, response to emergency situations, and difficulty steering.
  • 0.08 – reduced concentration, speed control, information processing capability, impaired perception, and short-term memory loss.
  • 0.10 – reduced ability to maintain lane position and brake appropriately.
  • 0.15 – substantially impaired vehicle control, attention to driving tasks, and visual and auditory information processing.

Illegal Drugs

According to the NHTSA, 56% of drivers involved in crashes resulting in fatalities or high-severity injuries tested positive for at least one drug.


Marijuana can also have a negative effect on driving skills. Potentially dangerous side effects include slowed reaction time, decreased coordination, reduced situational awareness, and impaired decision-making capabilities. Furthermore, studies have shown that marijuana use in combination with alcohol can lead to more severe impairment than either substance alone.

Other Illegal Drugs

Other illegal drugs, such as cocaine, methamphetamine (meth), and heroin, are associated with significant but varied effects on users and drivers. Cocaine and meth tend to make users more aggressive and reckless, making speeding, erratic driving, and dangerous traffic behavior more likely. Heroin tends to make users drowsy, making reaction times and decision-making dangerously slower while driving.

Prescriptions & Over-the-Counter Medications

According to the NHTSA, 10% of weekday, daytime drivers surveyed tested positive for prescription and/or over-the-counter drugs. Furthermore, a roadside survey reported that 22.5%, or 1 in 4, drivers tested positive for a drug that could impair driving ability – beyond alcohol and illegal drugs.


Prescription drugs are often taken for various medical conditions but can still impair driving skills if taken improperly or without consulting a doctor first. Common prescription drugs such as sedatives, opioids, and stimulants have all been linked to car accidents due to their effects on cognitive abilities and alertness while driving.

Over-the-Counter Medications

Over-the-counter medications such as antihistamines may also lead to drowsiness behind the wheel if taken improperly or at high doses.

Macon Car Accident Attorneys

It is vital for everyone who plans on getting behind the wheel of a car to understand how different substances can affect their ability to drive safely and responsibly. If you or someone you know has been involved in an accident due to an impaired driver, contact an experienced car accident attorney right away so they can help protect your legal rights during this difficult time. Knowing how different substances can impact your senses while driving is essential for ensuring safe roads for everyone involved!

Contact Adams Law Firm today by calling 478-772-3939 or filling out our secure online contact form.