No, Cannabidiol (CBD) Does Not Impair Driving

Soft Secrets
17 Feb 2021

It's a commonly asked question whether the use of cannabis can impair driving? Well, it does matter what kind of cannabis is in question. In a groundbreaking study, researchers with the University of Sidney demonstrated that CBD is entirely safe for driving. On the other hand, the psychoactive effects of THC need hours to disappear, which brings risks if you're operating a vehicle.

The interest in medical treatment using cannabis-derived products has been growing worldwide, in particular the increased use of CBD-infused products for various health conditions like anxiety, chronic pain, addictions, and epilepsy. A lot of the products available to treat any of these conditions may contain a mixture of both CBD and THC.

A lot of people have wondered whether cannabis medicines are safe to use when you have to operate a vehicle or a machine, but there has been little research on that, until now. 

Does Cannabidiol (CBD) Affect Driving? 

A landmark study by scientists from the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney and carried out at the Netherlands' Maastricht University has shown something to be expected: CBD is entirely safe as an active medical component of the cannabis plant, and does not impair ability to drive.   

However, the study pointed out that moderate THC intoxication produces mild driving impairment lasting up to four hours, which could have implications for drug-driving road regulations and overall management of medical cannabis.

“These findings indicate for the first time that CBD, when given without THC, does not affect a subject’s ability to drive. That’s great news for those using or considering treatment using CBD-based products,” said in a statement lead study author Dr. Thomas Arkell. 

The recent research involved 26 healthy participants inhaling vaporized cannabis containing different THC and CBD amounts, then going for a roughly 60 miles drive (100 km) in real-world controlled conditions, including driving on public highways both 40 minutes after inhaling and four hours afterward. A driving instructor accompanied each participant.

Cannabis containing mainly CBD was found not to affect driving, while cannabis with THC or a mix of CBD and THC was found to cause mild impairment measured at 40 minutes later; however, all-clear after four hours. Participants vaporized cannabis with mainly THC, mainly CBD, THC and CBD combined, or placebo products without active components. The THC amount vaporized by participants was enough to stir an intoxication sensation.

“With cannabis laws changing globally, jurisdictions are grappling with the issue of cannabis-impaired driving,” Dr. Arkell said. “These results provide much-needed insights into the magnitude and duration of impairment caused by different types of cannabis and can help to guide road-safety policy not just in Australia but around the world.”

“Road safety is a primary concern. These results should allow for evidence-based laws and regulation for people receiving medical cannabis,” he said.

Professor Ian McGregor, the Academic Director of the Lambert Initiative, noted that studying how cannabis affects driving with such precision in real-world situations is necessary.

“The results should reassure people using CBD-only products that they are most likely safe to drive, while helping patients using THC-dominant products to understand the duration of impairment,” McGregor said.

“While some previous studies have looked at the effects of cannabis on driving, most have focused on smoked cannabis containing only THC (not CBD) and have not precisely quantified the duration of impairment.

“This is the first study to illustrate the lack of CBD effects on driving and to also provide a clear indication of the duration of THC impairment,” he said.

How Weed Impairs Driving?

The use of cannabis, when it contains psychoactive components such as THC, may impair people's judgment. The motor coordination of the body is under impact, and there's also the alternated perception on time.

While some people may report that they feel more concentrated from smoking weed, including when driving, their chances to be involved in a road accident still increases. But research specifically points out to the distorted ability to perceive time and distance, and actually lack of driver's concentration as the biggest problems. 

Weed can lead to bad judgments on the road, unwanted distractions, and failure to read road signs clearly. Yet the most significant risk factor is when people combine weed and alcohol together. In that case, the danger of causing a highway mishap becomes much greater than when using just weed. Research implies that the combo of weed and alcohol doubles the risk of impaired driving. 

Is Driving While Stoned Common?

According to some research, it is. Research presented by The National Highway Traffic Safety Administration (NHTSA) says that drugs and alcohol are involved up to 11% of the time in motor vehicle crashes. The NHTSA report also shows an increase in the number of drivers who have tested positive on the presence of THC in their body. This may be due to the expanding legalization of cannabis in the U.S., including recreational and medical regulation.

On the other hand, some drivers who use weed claim that smoking actually helps their concentration, and therefore their ability to drive. While this may be true for the first few minutes of driving, research further suggests that the driver might get distracted later on, as concentration begins to drop. That might also depend on the amount of THC taken.

How to Get Home Safely?

As the NHTSA recommends, it’s best to pass the keys to a sober driver who can drive you to your final destination or wait until the effects of weed taper out. If you see a friend who’s too high to drive, take their keys and arrange for them to get home safely. Don’t worry about offending someone. You can apologize or say thank you later.

If you need to wait after smoking and having to drive, drink more water to sober up, and try not to mix alcohol. Don't forget that the effect of edibles may hit after an hour. So if you feel all right now before getting in the car, the high might overwhelm you while on the road. It may all depend on the amount of THC you take, but sometimes even little can infringe with statewide laws regulating road safety.

Final words? Weed is good. It helps you relax and makes you feel elated. But use it with caution! Don't let it be the reason to later have regrets in life, or worse case, be involved in a road accident with a tragic outcome.

Also read on Soft Secrets:

- Does Weed Affect Your Ability to Drive?

- What to Expect First Time Smoking? 

- Any Dose of Alcohol Increases THC Levels in Blood 

This article was last updated on February 16, 2024

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