This is an edited excerpt from the recently-released UN World Drug Report 2025.

The prevalence of past-year cannabis use by teenagers between 15 and 16 was 4,4%, almost the same as the adults up to the age of 64 (4,6%). That’s around 240 million people.

Research indicates the possible value of cannabis in a variety of therapeutic indications, but its non-medical use can lead to negative consequences in users, particularly the young.

Especially worrying is regular, heavy cannabis use in adolescence, since it can lead to even more severe and persistent negative outcomes than during adulthood.

This is because the adolescent brain is still developing and the early initiation of heavy use appears to disrupt the trajectory of normal brain development and have many adverse effects on cognitive functions such as attention, learning and memory.

In addition to somatic harms to the brain and to the respiratory and other systems, early intensive cannabis use brings with it a range of social and educational issues, including limited academic achievement and subsequent economic problems, although the causal pathways are complex.

The early initiation of cannabis use and regular consumption of products with high THC contents among adolescents and young adults may also be a risk factor for depression, anxiety disorders or psychoses

Those consequences depend on a variety of factors and include cognitive and psychomotor impairments, which may result in motor vehicle accidents and fatalities, newly developed cardiovascular symptoms, respiratory and other cancers and other harmful effects on the respiratory system because the drug is most often smoked.

Other negative consequences include gastrointestinal problems (nausea or vomiting), and the possible exacerbation of mental disorders (such as psychoses, depression, panic attacks and anxiety), including cannabis use disorders.

Around 1 in every 10 people who use cannabis develop a cannabis use disorder, with an estimated 22.6 million people, or 0.44 per cent of the global population, having such a disorder in 2021, according to the Institute for Health Metrics and Evaluation.

In Europe, the prevalence of cannabis use among young people aged 15 and 16 remains higher than among the general population aged between 15 and 64, according to new data from the European School Survey Project on Alcohol and Other Drugs.

However, there has been a significant decline in the prevalence of past-year cannabis use among young people from 12.3 per cent in 2019 to 9.0 per cent per cent in 2024.

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