A new peer-reviewed study published in the Journal of Adolescent Health has raised concerns about increasing teen cannabis use in California following the legalization of adult-use cannabis in 2018. Conducted by researchers from UC Irvine, UCLA, and the Public Health Institute’s Get It Right from the Start program, the study highlights a troubling upward trend in cannabis consumption among 11th graders.
The study, titled Local Cannabis Policy and Cannabis Use by California High School Students Before and After Statewide Retail Legalization, analyzed data from over 370,000 California teens through the California Healthy Kids Survey (CHKS). This annual survey, administered by the state Department of Education, tracks student health behaviors among 7th, 9th, and 11th graders. The findings revealed a clear shift in teen cannabis use patterns before and after legalization.
Prior to 2018, daily or near-daily cannabis use among high school juniors had been declining. However, after adult-use cannabis retailers began operating, teen cannabis use began climbing again by 2020.
The study also examined how local policies influence teen cannabis use. Jurisdictions that maintained bans on retail cannabis stores consistently reported lower rates of youth consumption, both before and after legalization. In contrast, areas that allowed storefront cannabis sales showed higher rates of teen cannabis use. Interestingly, regions permitting only medical-delivery cannabis did not experience the same spike.
Researchers noted that the increase in frequent teen cannabis use also coincided with the rise of higher-potency cannabis products. Items such as vapes, oils, and wax concentrates known for their strong THC levels have become more popular among young users. These products may pose a greater risk of dependency, cognitive issues, and even psychosis, making the findings particularly concerning for parents and educators.
Public health experts emphasize that while legalization has benefited the adult market, it also underscores the importance of strong youth prevention programs. The data shows that where regulations are stricter, teen cannabis use tends to remain lower.
Under current California law, individuals aged 18 and above can legally purchase cannabis with a doctor’s recommendation for medical use, while those 21 and older can buy it for recreational purposes. Despite these limits, teen cannabis use remains an issue that policymakers and communities must address.
As researchers continue to monitor trends, this study serves as a critical reminder that legalization requires equally strong education and prevention strategies to protect teens from the long-term impacts of teen cannabis use.
