The use of the Cannabis sativa plant as a medicinal plant dates back to around 2700 BC, and although its popularity as a therapeutic declined in the twentieth century, in recent decades it is once again being used to treat epilepsy, chronic pain, loss of appetite (especially as a consequence of chemotherapy), and certain inflammatory diseases. Much of the research has focused on the most well-known phytocanabinoid (pCB), trans-Δ9 tetrahydrocannabinol (THC), however because of its effects on the central nervous system its use as an anti-inflammatory agent is limited. The Cannabis sativa plant contains more than a hundred compounds classified as cannabinoids, and many of these are not psychoactive but might have similar effects on the immune system, and could be exploited as anti-inflammatory treatments.