Smoking cannabis can halve the severity of OCD (obsessive-compulsive disorder) symptoms.
OCD sufferers report their compulsive behaviour fell by 60 percent and unwanted thoughts by 49 percent within four hours of smoking cannabis.
Cannabis with higher concentrations of CBD, or cannabidiol, were even more effective, say researchers from Washington State University.
The good effects are short-lived, however, but the results do point to a longer-lasting solution, say the researchers.
They tracked the use of cannabis by 87 volunteers with OCD, who logged more than 1800 sessions over the 31 months of the trial. The good effects also lessened the more they smoked cannabis, suggesting they were building up a tolerance.
(Source: Journal of Affective Disorders, 2020; doi: 10.1016/j.jad.2020.09.124)