Cannabidiol (CBD) constitutes up to 40% of cannabis sativa plant and has quite different psychological effects to the plant's best-known constituent, delta-9-tetrahydrocannabinol (delta-9-THC). This study examines the current knowledge of the effects of CBD on anxiety.

Articles were identified through a search of MEDLINE using the key word cannabidiol and anxiety. No search limits were included. Additional references were located through review of the bibliographies of the articles identified.

In animal studies CBD has shown similar effects to anxiolytic drugs in conditioned emotional paradigms, the Vogel conflict test, and the elevated plus maze test. In humans, oral administration of CBD in healthy volunteers decreases and antagonizes the anxiogenic effect of high doses of delta-9-THC. CBD may thus posses inherent anxiolytic properties unrelated to THC-type activity. This is consistent with its anxiolytic effect on anxiety elicited by simulated public speaking test. In addition, SPECT and fMRI neuroimaging studies have confirmed that CBD has anti-anxiety properties and that these effects are mediated by an action on limbic and paralimbic brain areas.

These results support the hypothesis that CBD may be a future therapeutic option for anxiety. However, future studies of CBD in clinical anxiety such as panic and social anxiety disorder and comparative studies of its anxiolytic effects with those produced by benzodiazepines and other anti-anxiety compounds are clearly indicated.