Cannabis Edibles and Driving: What You Need to Know

by Jon Scaccia July 1, 2024

With the legalization of cannabis in many places, people are experimenting with various ways to consume it, including edibles. However, there’s been growing concern about how cannabis edibles affect driving abilities. A recent study delves into this issue, providing valuable insights that every driver and public health practitioner should be aware of.

Understanding the Study

Researchers wanted to explore how eating cannabis edibles affects driving. To do this, they recruited 22 participants who regularly used cannabis and asked them to drive a simulator before and after consuming their preferred edible. The same participants also drove the simulator without consuming any cannabis as a control test. The goal was to compare their driving performance in both scenarios.

Key Findings

Driving Speed and Performance:

• After consuming edibles, participants’ average driving speed decreased two hours post-consumption.
• However, this effect was not observed at four and six hours after consumption.
• Under conditions where participants had to perform a secondary task while driving, changes in speed were not significant after adjusting for multiple comparisons.
• There were no significant changes in how much participants swerved (standard deviation of lateral position), their maximum speed, speed variability, or reaction time at any point.

Blood THC Levels:

• THC levels in the blood were significantly higher after consuming the edible compared to the control.
• However, these levels remained relatively low (around 2.8 ng/mL) two hours after consumption.
• Interestingly, there was no direct correlation between blood THC levels and driving impairment.

Subjective Experience:

• Participants reported feeling the effects of the edible for up to seven hours.
• They felt less willing and less able to drive for up to six hours after consumption, indicating that the edibles were indeed intoxicating.

Why This Matters

This study is crucial because it highlights that cannabis edibles can impair driving, even if the levels of THC in the blood are low. This finding challenges the current legal thresholds for blood THC levels while driving, which are primarily based on studies involving smoked cannabis. Since edibles lead to different THC absorption and metabolism, these legal limits might not be applicable for edibles.

Implications for Public Health and Safety

For public health practitioners and policymakers, these results underscore the need to re-evaluate how we assess cannabis impairment on the road. Here are a few reasons why this is important:

1. Different Absorption Rates:
   • Unlike smoking, edibles result in lower but more prolonged levels of THC in the blood, which can still impair driving.
2. Legal Thresholds:
   • Current legal limits for THC might not effectively identify impairment from edibles, suggesting a need for new standards or testing methods.
3. Public Awareness:
   • Educating the public about the delayed and prolonged effects of edibles on driving can help reduce the risk of accidents.

What You Should Do

If you consume cannabis edibles, it’s crucial to be aware of their long-lasting effects. Here are some tips to stay safe:

• Wait it Out: Avoid driving for at least six hours after consuming edibles.
• Plan Ahead: Arrange for alternative transportation if you plan to consume edibles.
• Educate Yourself: Understand that even if you don’t feel “high,” your driving abilities may still be impaired.

Encouraging Responsible Use

Public health campaigns should focus on the unique effects of edibles compared to smoked cannabis. Let us know your experiences in the comments!:

1. Have you ever experienced the effects of cannabis edibles? How did it compare to smoking cannabis in terms of how you felt and how long it lasted?
2. What steps do you think should be taken to better educate the public about the risks of driving after consuming cannabis edibles?

Conclusion

This study is a significant step toward understanding the impact of cannabis edibles on driving. It reveals that while blood THC levels may remain low, the subjective experience of intoxication and the risk of driving impairment are real and prolonged. As legalization spreads and more people turn to edibles, it’s crucial to develop accurate testing and public education to ensure road safety.

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About the Author

Dr. Jonathan P. Scaccia, PhD, is a clinical-community psychologist with expertise in public health science and practice. He has led evaluation and research initiatives focusing on health equity, vaccine distribution, and organizational readiness. Dr. Scaccia has contributed to federal suicide prevention programs and vaccine equity strategies. He has been recognized for his impactful work and is a leading voice in advancing public health practices.