This document discusses the history and biology of medical cannabis in the UK. It provides key dates in the UK regarding cannabis cultivation, medical use, and legislation. It then covers the biology of the endocannabinoid system and cannabinoid receptors. The remainder discusses evidence for using cannabis to treat MS symptoms like spasticity through its effects on the endocannabinoid system and inhibitory neurotransmission. It also discusses the use of Sativex and different policies around medical and recreational cannabis internationally.