Variations in Regulated Cannabis Sales Conditions and Their Effect on Purchase Behaviour: Findings from an Observational Study

Introduction: Many countries are exploring regulations for non-medical cannabis markets to mitigate cannabis-related health risks. Regulations such as restricting opening hours or product variability may be useful tools, yet their effects on cannabis purchases remain understudied due to a lack of comprehensive sales data. Methods: The Züri Can study implements a framework for strictly regulated cannabis sales, with a fixed product portfolio and a maximum purchase volume. The dataset contains all tracked purchases of 2,507 participants from August 22, 2023, to January 17, 2025, across ten Cannabis Social Clubs (CSCs), ten pharmacies, and the municipal Drug Information Centre Zurich (DIZ). It captures detailed information on sales conditions (opening hours, product variety, customers per hour) and purchase behaviour (purchase frequency, number of packages per purchase, THC volume, and expenditure per package). Generalised estimating equations provided means and confidence intervals by type of point of sale (POS). Multilevel survival analysis and random coefficient models examined how sales conditions influenced purchase behaviour, and how purchase behaviour evolved over time. Results: Pharmacies had notably more weekly operating days (5.66), longer daily opening hours (6.16), and fewer customers per hour (1.08) than CSCs (3.81 days; 3.76 h; 4.62 customers per hour) and the DIZ (2.85 days; 3.28 h, 3.37 customers per hour). However, compared to the POS average, longer opening hours and more customers per hour only slightly increased purchase frequency; their impact on purchase amount was negligible. Variations in the number of available products only marginally affected purchasing behaviour. Purchase frequency was higher in the 30 days following the first purchase and declined over 12 months (CSCs, pharmacies) or remained stable (DIZ) while amount obtained per purchase remained stable. Conclusion: These findings suggest that in a strictly regulated non-medical cannabis market similar to the framework of the Züri Can study, variations in sales conditions only have a small impact on purchase behaviour. Legal access to cannabis does not inherently lead to increased purchasing and may even contribute to a decline in purchase frequency.