Tetrahydrocannabinol (THC) is one of at least 113 cannabinoids identified in cannabis. THC is the principal psychoactive constituent of cannabis. With chemical name (−)-trans-Δ⁹-tetrahydrocannabinol, the term THC also refers to cannabinoid isomers.
THC is an active ingredient in Nabiximols, a specific extract of Cannabis that was approved as a botanical drug in the United Kingdom in 2010 as a mouth spray for people with multiple sclerosis to alleviate neuropathic pain, spasticity, overactive bladder, and other symptoms. Nabiximols (as Sativex) is available as a prescription drug in Canada.