Effects of legal access versus illegal market cannabis on use and mental health: A randomized controlled trial

Abstract Aims: We measured the effects of public health‐oriented cannabis access compared with the illegal market on cannabis use and related mental health outcomes in adult cannabis users. Design: This was a two‐arm, parallel group, open‐label, randomized controlled trial. Follow‐up outcome measurement took place after 6 months. Setting: The study was conducted in Basel‐Stadt, Switzerland. Participants: A total of 378 adult (aged ≥18 years) cannabis users were enrolled and randomized between August 2022 and March 2023, although only 374 users