Recent years have seen a dramatic increase in the number of clinical trials investigating the potential efficacy of medicinal cannabinoids for the symptomatic treatment of chronic pain and spasticity in multiple sclerosis (MS). A number of different cannabinoids have been used, including: delta9-tetrahydrocannabinol (THC) itself; the synthetic delta9-THC, dronabinol; a 1:1 ratio of delta9-THC:cannabidiol (Sativex); and the synthetic delta9-THC metabolites CT-3 and nabilone. Other Cannabis extracts have also been tested. While 2-3 years ago there was little consensus in the literature, now the majority of studies are beginning to suggest that cannabinoids are useful in the treatment of MS in at least a subset of individuals. Their adverse side-effect profile has generally been mild compared with other drugs used for pain and spasticity; nonetheless, there is still concern about potential long-term side effects, particularly psychiatric side effects and effects on fetal development.