The first study to use a cannabis-based medicine (CBM) for treating rheumatoid arthritis has found that it has a significant effect on easing pain and on suppressing the disease.

... the researchers say that although the differences were small and variable in the group of 56 patients they studied, the results are statistically significant and a larger trial is needed to investigate in more detail the effects of CBM on the disease which affects approximately 600,000 people in the UK (1 in 100 of the population).[2]

... (this) is the first randomised controlled trial to investigate the effect of a CBM on RA.

... the researchers randomised 31 patients to receive the CBM and 27 the placebo. The CBM (brand name: Sativex) was in the form of an easy-to-use mouth spray that patients could administer themselves up to a maximum of six doses a day.

... The CBM consisted of a blend of whole plant extracts, standardised for content, that delivered approximately equal amounts of two key therapeutic constituents from the cannabis plant: ∆-9-Tetrahydrocannabinol (THC) and cannabidiol (CBD).

Mouse studies have shown that THC and CBD have anti-inflammatory effects, and that CBD blocked progression of RA and produced improvements in symptoms.

Call me a sceptic, but those who have rheumatoid arthritis might want to wait until all the safety data is in, and sufficient time has elapsed such that a determination can be made on "long term" safety involving an uncertain link between cannabis and psychosis.