Tetrahydrocannabivarin (THCV, THV) is a homologue of tetrahydrocannabinol (THC) having a propyl (3-carbon) side chain. This terpeno-phenolic compound is found naturally in Cannabis, sometimes in significant amounts. The psychoactive effects of THCV in Cannabis preparations are not well characterized. Plants with elevated levels of propyl cannabinoids (including THCV) have been found in populations of Cannabis sativa L. ssp. indica (= Cannabis indica Lam.) from China, India, Nepal, Thailand, Afghanistan, and Pakistan, as well as southern and western Africa. THCV levels up to 53.7% of total cannabinoids have been reported.   THCV has been shown to be a CB1 receptor antagonist, i.e. it blocks the effects of THC.