CBD Up to 1,500 mg Did Not Impair Driving or Cognitive Function in a Crossover Trial | Research

The takeaway

Oral CBD at doses up to 1,500 mg did not impair simulated driving performance or cognitive function compared to placebo, though CBD persisted in plasma for over 4 weeks at the highest dose.

CBD users concerned about driving, regulators, workplace safety researchers

No driving impairment at any CBD dose up to 1,500 mg

What the researchers found

Non-inferiority analyses established that CBD at 15, 300, and 1,500 mg did not impair driving performance beyond a threshold equivalent to 0.05% blood alcohol. CBD did not induce feelings of intoxication or impair cognitive function. Unexpectedly, CBD at 1,500 mg persisted in plasma for more than 4 weeks.

Why it matters

CBD is widely consumed in both prescription and non-prescription products, yet its effects on safety-sensitive tasks have been under scrutiny. This study provides reassuring evidence that even high doses do not impair driving.

The numbers in context

17 participants; 4 CBD doses (placebo, 15, 300, 1500 mg); non-inferiority threshold: 0.05% BAC equivalent; CBD detectable in plasma >4 weeks at 1500 mg

How the study worked

Double-blind, placebo-controlled, crossover RCT in 17 healthy adults. Four sessions: placebo, 15 mg, 300 mg, or 1,500 mg oral CBD. Simulated driving assessed at ~45-75 and ~210-240 minutes post-treatment. Primary outcome: standard deviation of lateral position (SDLP).

What this study cannot tell us

Small sample (n=17). Single-dose acute administration only. Simulated driving, not real-world. May not generalize to chronic CBD users or those taking CBD with other medications.

How to read the evidence

Well-designed double-blind crossover RCT with validated driving measures, but small sample size (n=17).

When this study was published

Published in 2022

The bigger picture

While THC clearly impairs driving, this study adds to evidence that CBD does not. The long plasma persistence of high-dose CBD may have implications for drug testing but does not appear to affect function.

Questions still open

Could the prolonged plasma persistence of CBD cause false-positive drug tests? Would chronic high-dose CBD use produce different driving effects than acute dosing?

Common questions

Can you drive after taking CBD?

This study found oral CBD at doses up to 1,500 mg did not impair simulated driving performance or cause feelings of intoxication. Driving performance was not worse than the equivalent of 0.05% blood alcohol at any dose.

How long does CBD stay in your system?

At 1,500 mg, CBD was detectable in plasma for more than 4 weeks. Lower doses cleared faster. This prolonged presence did not affect driving performance or cognition.

Read the original research

Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial.

Journal of psychopharmacology (Oxford, England), 36(12), 1338-1349

View on PubMed ↗Publisher’s paper ↗

Citation

McCartney, Danielle; Suraev, Anastasia S; Doohan, Peter T; Irwin, Christopher; Kevin, Richard C; Grunstein, Ronald R; Hoyos, Camilla M; McGregor, Iain S. (2022). Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial.. Journal of psychopharmacology (Oxford, England), 36(12), 1338-1349. https://doi.org/10.1177/02698811221095356