Cannabis use is relatively common in the European Union (EU) and Norway, with around
23 million people (6.8 % of all 15- to 64-year-olds) having used the drug in the past year and about 12 million (3.6 % of all 15- to 64-year-olds) in the last month. Although the prevalence of last-year cannabis use among the general population is generally stable or decreasing in man countries, demands for treatment in which cannabis is the primary drug continue to rise, indicating a possible increase in related problems. The substance is currently the most frequently mentioned drug by those demanding drug treatment for the first time in the EU and Norway. This suggests that, even though most cannabis use at the population level is likely to be transitory and at low levels, a significant minority of users use the substance intensively and/or for long periods of time. These patterns of use are reported to be associated with harms to the user and possibly with a need for treatment. Although this problem has been increasingly recognised, knowledge of the prevalence of the more intensive forms of cannabis use has been limited at the EU level.