Adolescent polysubstance use: Time for a new public health approach Ronan Fleury and Mary Cannon discuss the growing trend of polysubstance use among adolescents and highlight the need for a new public health strategy that reflects the complexities of adolescent substance use. Adolescent substance use is no longer a single-substance issue. Increasingly, young people use alcohol, nicotine, and cannabis together, a pattern that research shows is both common and harmful. In a recent Irish school survey, 7.5% of 15–16-year-olds reported using all three substances within the past month (Fleury et al., 2025). This trend challenges long-standing public health frameworks that still approach substance use in isolation, leaving us with definitions, policies, and interventions that lag behind lived reality. Clinical trials and neuroscience studies have historically excluded people who use multiple substances (Hakkararinen et al, 2019). The result is evidence that does not reflect reality. We end up with prevention strategies and clinical interventions that are not only mismatched but sometimes irrelevant to the populations most in need.
Fleury et al. (2025) studied this question.