Effects of THC on driving performance, physiological state and subjective feelings relative to alcohol.
Adi Ronen, Pnina Gershon, Hanan Drobiner, Alex Rabinovich, Rachel Bar-Hamburger, Raphael Mechoulam, Yair Cassuto, David Shinar
Accident; Analysis and Prevention May 2008 DOI: 10.1016/j.aap.2007.10.011 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Peer reviewed |
|---|---|
| Sample size | 14 |
| Population | Healthy students, all recreational marijuana users |
| Intervention | Alcohol |
| Dose | 13 mg and 17 mg THC cigarettes; alcohol to 0.05% BAC |
| Duration | 24 hours post-smoking high dose THC |
| Topics | Cannabis |
| Key findings | Both THC doses impaired driving in a dose-dependent manner, with the low dose (13 mg) comparable to moderate alcohol (0.05% BAC) on some measures. THC increased physical effort and discomfort, while alcohol increased sleepiness. THC led to slower driving, alcohol to faster driving, and no THC effects persisted at 24 hours. |
Abstract
The effects of marijuana or THC on driving has been tested in several studies, but usually not in conjunction with physiological and subjective responses and not in comparison to alcohol effects on all three types of measures. To assess the effects of two dosages of THC relative to alcohol on driving performance, physiological strain, and subjective feelings. We tested the subjective feelings and driving abilities after placebo, smoking two dosages of THC (13 mg and 17 mg), drinking (0.05% BAC) and 24 h after smoking the high dose THC cigarette, while monitoring physiological activity of the drugs by heart rate. Fourteen healthy students, all recreational marijuana users, participated in the study. Both levels of THC cigarettes significantly affected the subjects in a dose-dependent manner. The moderate dose of alcohol and the low THC dose were equally detrimental to some of the driving abilities, with some differences between the two drugs. THC primarily caused elevation in physical effort and physical discomfort during the drive while alcohol tended to affect sleepiness level. After THC administration, subjects drove significantly slower than in the control condition, while after alcohol ingestion, subjects drove significantly faster than in the control condition. No THC effects were observed after 24 h on any of the measures.
Comparable studies
Other randomized controlled trials on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment Healthy participants | 2012 | Randomized controlled trial | n = 48 |
| Distinct Effects of Δ9-Tetrahydrocannabinol and Cannabidiol on Neural Activation During Emotional Processing Healthy, English-native, right-handed men who had used cannabis 15 times or less in... | 2009 | Double-blind, randomized, placebo-controlled crossover trial | n = 15 |
| Acute Effects of a Single, Oral dose of d9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) Administration in Healthy Volunteers Healthy male subjects | 2012 | Randomized controlled trial | n = 16 |
| Modulation of Mediotemporal and Ventrostriatal Function in Humans by Δ9-Tetrahydrocannabinol Healthy, native English-speaking, right-handed men of white race/ethnicity who had used... | 2009 | Randomized controlled trial | n = 15 |
| Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition Healthy volunteers with a history of light cannabis use | 2019 | Randomized, double-blind, within-subjects crossover | n = 14 |
Citations in the library
Cited by 8
- Cannabis smoking impairs driving performance on the simulator and real driving: a randomized, double‐blind, placebo‐controlled, crossover trial Fundamental and Clinical Pharmacology May 12, 2018
- Acute psychomotor, memory and subjective effects of MDMA and THC co-administration over time in healthy volunteers Journal of Psychopharmacology September 3, 2010
- The effect of cannabis edibles on driving and blood THC. Journal of Cannabis Research May 31, 2024
- Potency-related effects of smoked cannabis on simulated driving performance: a randomized, controlled crossover trial. Scientific Reports March 10, 2026
- Combined effect of alcohol and cannabis on simulated driving. Psychopharmacology May 2022
and 3 more in the library