California teenagers consistently perceive cannabis as less harmful than other commonly used substances, according to a new study that analyzes data from two large surveys of schools across the state. Shu-Hong Zhu, PhD, professor at the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science and co-authors, examined how teenagers view the risks of daily and occasional cannabis use compared to alcohol, nicotine vapor and cigarettes, based on responses from more than 175,20 students and 2,000 respondents. 2024.
The findings show a clear and persistent pattern: cannabis is seen as the least harmful substance among respondents. In the previous survey, around two-thirds of teenagers thought regular cannabis use was harmful, compared to higher rates for alcohol, vaping and cigarettes. While perceptions of harm were lower across all substances for occasional use, cannabis remained the least concerning for teenagers. These trends remained stable in the 2024 data, suggesting that adolescents’ relatively low perception of cannabis-related risk remained stable over time.
The study also found significant differences based on age, experience and social environment. Unlike alcohol and tobacco products—where perceived harm generally stayed the same or increased with grade level—perceptions of the danger of cannabis decreased as students got older. Younger teens were more likely to view cannabis as harmful, but this perception waned significantly by 12th grade. Additionally, teens who had used a substance were less likely to view it as harmful, with the largest perception gap seen for cannabis. Peer influence also played an important role: Teens with more friends who used a substance consistently rated it as less harmful, with the strongest effect again seen for cannabis.
These findings raise public health concerns, as lower perceived risk is often associated with higher likelihood of use. Although overall adolescent cannabis use has declined in recent years, researchers note that it remains a concern because of potential effects on brain development, cognition and mental health. The authors suggest that prevention and education efforts may need to better address the risks associated with cannabis, particularly as changing social norms and increased exposure to pro-cannabis messages may affect how young people perceive its safety.
The study was published on May 5, 2026 at Drug and alcohol addiction.
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