New research published in Tobacco Control reveals a troubling trend. The legalisation of cannabis in the United States has coincided with a significant increase in cannabis and tobacco co-use among adults. Meanwhile, sole tobacco consumption has declined.

The study analysed health data from 854,878 Americans across 38 states between 2016 and 2023. Results showed that concurrent cannabis and tobacco use rose from just over 4% to nearly 5.5% during this period. Perhaps more concerning, the likelihood of this combined usage increased by 44% following legalisation.

Cannabis and Tobacco Co-Use Patterns Across Demographics

Dr Sharon Hawkins and her research team discovered that cannabis and tobacco co-use is spreading beyond traditionally high-risk groups. Older adults aged 65 and over saw their cannabis consumption increase by 2.5%. Meanwhile, those with higher education levels experienced a near-doubling of concurrent use from roughly 1% to around 2%.

“Adults are shifting product use in response to cannabis legalisation,” the researchers noted, highlighting how changing legislation appears to be reshaping substance use behaviours across diverse populations.

The data showed stark geographical variations. Sole tobacco use ranged from 8% in Massachusetts to 26% in West Virginia, whilst concurrent cannabis and tobacco use peaked at 9.5% in Alaska and bottomed out at just over 3% in Utah.

Mental Health Concerns Mount

Adults reporting poor mental health emerged as particularly vulnerable. This group not only showed larger increases in sole cannabis use compared to those with good mental health but also demonstrated more pronounced shifts in their substance use patterns overall.

The study tracked usage across several demographic factors. These included age, sex, educational attainment, race, marital status, health insurance coverage, and alcohol consumption. Higher risk groups consistently included younger adults, males, single individuals, those without health insurance, and people reporting heavy drinking alongside poor mental wellbeing.

Retail Stores Drive Concurrent Cannabis and Tobacco Use

Opening licensed recreational cannabis retail stores appeared to amplify these trends. Further analysis revealed that the establishment of legal retail outlets correlated with additional increases in both sole cannabis use and cannabis and tobacco co-use.

Overall, sole cannabis use jumped by 88% after legalisation, whilst sole tobacco use fell by 13%. From 2016 through 2023, sole tobacco and cannabis use remained relatively stable at 14% and 7%, respectively, but the rise in concurrent cannabis and tobacco use tells a different story.

Why Concurrent Use Matters

Health experts have raised concerns about combined substance use for good reason. Research indicates that concurrent cannabis and tobacco use carries an increased risk of developing dependence. Emerging evidence suggests this combination may produce worse health outcomes than using either substance alone.

As of July 2025, 24 US states plus Washington DC had legalised cannabis for adults aged 21 and over. This represents a dramatic shift since Colorado and Washington became the first states to do so in 2012.

Methodological Limitations

The researchers acknowledged several constraints in their observational study. The Behavioural Risk Factor Surveillance System, whilst comprehensive, relies on self-reporting. It doesn’t capture detailed information about timing, frequency, or methods of using tobacco and cannabis together. With only 38 states participating, the findings may not apply universally across America.

Despite these limitations, the study’s scale and timeframe provide valuable insights into how legislative changes affect public health behaviours.

Policy Implications

The research team warned that changing policy through legalisation has multiple effects. Increasing product access via retail stores and rising public perceptions of cannabis safety “could lead to increases in co-use of tobacco and cannabis through multiple pathways.”

Paradoxically, whilst cannabis and tobacco co-use climbs, overall tobacco restrictions continue tightening. This creates competing pressures that appear to be reshaping substance use patterns rather than simply reducing them.

The study notes that these shifting patterns may be narrowing disparities in use. This happens due to rising levels among populations less likely to use cannabis rather than declining use among higher-risk groups. In other words, legalisation isn’t primarily reducing consumption among heavy users. Instead, it’s introducing new users to both substances.

Looking Ahead

Twenty-four states have now legalised recreational cannabis. More will likely follow. Understanding how these policy changes influence substance use behaviours becomes increasingly crucial for public health planning. This is especially true for cannabis and tobacco co-use.

The findings raise important questions about unintended consequences. As cannabis becomes more socially acceptable and legally accessible, are we inadvertently creating new pathways to dual substance use? The evidence suggests we are.

For health professionals, policymakers, and communities, this research underscores the need for careful monitoring. As legalisation continues to expand across America and potentially to other countries, tracking concurrent cannabis and tobacco use patterns becomes critical.

Source: medical