Cannabis use in teenagers is rising in ways that many communities have not yet fully reckoned with. It remains the most commonly used federally illicit substance among young people in the United States. A major study published in JAMA Network Open in April 2026 followed over 1.3 million screening questionnaires from adolescents aged 13 to 17 at Kaiser Permanente Northern California, spanning January 2011 to December 2024. Researchers examined how cannabis use shifted across two turning points: California’s recreational cannabis legalisation (RCL) and the COVID-19 pandemic. The findings carry real implications for how we approach young people, policy and prevention.

What the Study Found: Cannabis Use Rose After Legalisation

Before California legalised recreational cannabis in November 2016, rates among young people had been falling. In January 2011, around 10.4% of adolescents reported past-year cannabis use. By October 2016, just before legalisation passed, that figure had dropped to 6.8%.

That downward trend did not last.

After Proposition 64 passed, rates began to climb. By December 2017, just before legal retail sales opened, the rate had risen to around 8.1%. As adult-use stores opened and normalised access further, the upward trend continued, reaching around 9.5% by early 2020.

Cannabis use in teenagers responds to the broader environment. Social attitudes, perceived legal risk and product availability all play a role. Researchers found the post-legalisation increase was gradual, not sudden, which points to shifting perceptions of harm rather than one dramatic change.

Other research has linked rises in cannabis use following legalisation to increases in cannabis use disorder, cannabis-related emergency department visits and hospital encounters for psychosis among young people. This is not a trend communities can afford to ignore.

How the COVID-19 Pandemic Changed Cannabis Use in Teenagers

The pandemic brought dramatic disruption. School closures, shelter-in-place orders and reduced social contact reshaped daily life for young people almost overnight.

Researchers found that rates of cannabis use among teenagers fell sharply after the pandemic began. By December 2024, the rate had declined to around 6.5%, returning to levels not seen since before legalisation.

This fall happened even as adolescent mental health worsened. Depression, anxiety and self-injury among young people all increased during the pandemic. The two trends moved in opposite directions. That suggests the decline in cannabis use was not about improved wellbeing. Reduced social interaction, greater parental presence at home and fewer opportunities to access substances in social settings all played a part.

Rates continued to fall slightly even after restrictions lifted, staying below pre-legalisation levels through the end of 2024.

Why Cannabis Use in Teenagers Matters

Adolescence is a critical window of brain development. Cannabis use during these years carries distinct risks that differ from those faced by adults. Early and regular use links to poorer outcomes across neurocognitive development, mental health, educational attainment and later substance use.

The teenage brain is still forming. The earlier cannabis use begins, the greater the potential for lasting disruption. This is established neuroscience, not opinion.

The study tracked any past-year use rather than frequency or intensity. The true picture of problematic use may be more complex than headline figures suggest. That is precisely why consistent screening and honest conversations about risk matter.

What This Means for Communities

These findings point to several things worth acting on.

Cannabis use in teenagers does not exist in a vacuum. It responds to the world young people live in: the legal status of cannabis, the presence of retail outlets, shifts in perceived risk and everyday social conditions. When conditions change, use patterns change with them.

The pandemic decline shows that fewer opportunities to encounter substances in social settings leads to lower use. The environments where young people spend their time genuinely shape their choices.

Universal screening during routine healthcare visits also proved its value in this research. Standard well-child visits included a straightforward question about cannabis use as part of a broader health questionnaire. Consistent, non-stigmatising enquiry enables early identification that might otherwise be missed.

By 2024, rates had returned to pre-legalisation levels. That is encouraging. But it is not a conclusion. Ongoing attention to the factors shaping young people’s choices remains essential.

Supporting Young People

Cannabis use in teenagers rises and falls in response to broader social forces. That is not a reason for fatalism. It is a reason for purposeful action.

Parents and carers who talk openly with young people about cannabis build the kind of trust that makes those conversations count. Schools that place substance use within a wider conversation about wellbeing give young people real tools for decision-making. Communities that pay attention to where young people spend their time create the conditions for protective factors to take hold.

The environments we create and the conversations we have genuinely make a difference.

Source: dbrecoveryresources