As more countries consider legalizing non-medical cannabis, new research shows that prominent health warnings and less attractive packaging can reduce its appeal among young people.

In a recent study, researchers from the University of Waterloo found that the amount of advertising and promotion provided on packages changes how people see the product—whether they find it appealing to use or believe it's harmful. 

"Brand imagery on packaging helps to promote a product by sending signals about whether it's a 'cool' product, what kind of lifestyle it projects, and whether its product for males or females—all of which are associated with greater interest and appeal among youth," said David Hammond, a professor in Waterloo's School of Public Health Sciences. "If jurisdictions that legalize cannabis are interested in protecting youth, our data suggest that packaging restrictions and comprehensive health warnings are effective ways of doing that.

Canada was among the first countries to have legalized non-medical cannabis in October 2018. As part of federal regulations, Canada implemented comprehensive restrictions on advertising and promotion, including limits on the colours and logos displayed on cannabis packaging and mandatory health warnings. In contrast, US states that have legalized non-medical cannabis have fewer restrictions on pack marketing and less prominent health warnings.

The team of researchers conducted experimental surveys with 45,378 participants from Canada and the United States. The participants were randomized to view different cannabis packages, ranging from no brand imagery and uniform colours to full brand imagery. Participants were also asked to assess how the products' appeal differed based on perceived harm and how easy it is to remember warning messages, which addressed pregnancy, adolescent risk and impaired driving.

The researchers found that reducing the amount of brand imagery modestly decreased product appeal. The amount of branding also influenced perceptions of harm: products were rated significantly less harmful when packaged in full branding. In addition, participants' recall for health messages was significantly higher for the type of warnings mandated in Canada compared to when the warnings were presented using the format required in most US states that have legalized cannabis.

"Canada's warning messages on cannabis products are more salient and easier to recall than in the US," Hammond said. "Overall, our findings suggest that Canada's comprehensive regulations appear to be achieving their goal, which is to inform consumers about risks and reducing appeal, including among young people."

The study, Influence of package colour, branding and health warnings on appeal and perceived harm of cannabis products among respondents in Canada and the US, authored by Hammond, Samantha Goodman, Vicki Rynard and Maryan Iraniparast, will appear in the journal Preventive Medicine.