Impact of the legalisation of recreational cannabis use.

In recent years, there have been important legislative changes in many countries regarding the use of cannabis for medicinal and/or recreational purposes, which have facilitated access to it.  Uruguay, Canada and some of the US states are the only jurisdictions that have legalised recreational consumption, applying different legislative models. The aim of this review is to analyse the effects that the legalisation of recreational cannabis has had on its use and its consequences. In general, the evidence accumulated to date indicates that the legalisation of cannabis has been associated with a decrease in the price of the substance, higher concentration of THC (potency), greater diversity of presentations for consumption, lower risk perception and an increase in consumption in adults and moderately in adolescents (even though it is illegal for them to consume), as well as an increase in the adverse consequences derived from cannabis consumption on public health. There has been a decrease in drug-related arrests, but the illegal market continues to be frequently used. No increase in the demand for treatment due to cannabis consumption has been detected. Therefore, these legislative changes have so far failed to achieve their main objectives, which were to suppress the illegal market and protect the most vulnerable groups, while on the contrary, they seem to imply an increase in some of the negative aspects associated with cannabis consumption. However, taking into account that most of these legislative changes have entered into force relatively recently, a longer follow-up period is required to be able to draw definitive conclusions.