Cannabis is one of the most widely used drug worldwide, and it has also been legalized in several states in the US, Canada, and other countries around the world. The increased consumption of cannabis is associated with psychiatric symptoms, but the data available on this topic is not evident. This study aims to evacuate the psychiatric symptoms caused by the intake of cannabis constituents.

This systematic review and meta-analysis included 19 studies from Embase, PsycINFO, and MEDLINE that reported psychiatric symptoms of using oral or nasal CBD/THC constituents. The primary outcome of the study was psychiatric events in healthy participants measured by total, positive, and negative PANSS and BPRS scores.

Of the 19 studies included in the analysis, 15 reported the administration of THC and four of CBD plus THC. When compared with placebo, THC increased the severity of psychiatric outcomes, and that too, with a large effect size. The findings further suggested that out of the four studies, including THC plus CBD, only one was associated with a significant reduction in symptoms.

The research concluded that THC administration induced psychiatric, psychotic, and negative symptoms with large effect sizes. Furthermore, there was no consistent association between symptom reduction with the consumption of CBD.