Cannabis and tobacco co-use: A ‘joint’ challenge for research and practice

Cannabis and tobacco are two of the most commonly used substances worldwide, and are commonly co-used. 'Co-use' may comprise concurrent use (i.e. both substances used in the same time period) or 'co-administration' (i.e. simultaneous use in the same product). In Europe, cannabis is almost exclusively co-administered with tobacco. Historically, the measurement of cannabis-tobacco co-use has been insufficient, preventing accurate conclusions about prevalence and health effects. This has crucial implications for the health of consumers, understanding how to treat problematic use and monitoring the impact of changes in legalization. This symposium aims to highlight the importance of measuring and responding to cannabis and tobacco co-use in research and clinical practice. It will bring insight from countries where co-administration is less common (e.g. Canada, USA, Australia, New Zealand), to consider how to tackle this problem in Europe.