“Cannabis is mostly grown under illegal and unregulated circumstances, which seems to favour a product increasingly high in its main cannabinoid ∆-9-tetrahydrocannabinol (THC). ∆-9-tetrahydrocannabivarin (THCV) is a relatively untested cannabinoid which is said to be a cannabinoid receptor neutral antagonist, and may inhibit the effects of THC.

In this first study of THC and THCV, THCV inhibited some of the well-known effects of THC, while potentiating others.”

http://www.ncbi.nlm.nih.gov/pubmed/26577065