Factors Influencing Co-Use of Tobacco and Cannabis Amongst Young Adults in UK Further Education Colleges: A Qualitative Study.

Introduction: Tobacco and cannabis are commonly co-used (i.e., used concurrently or co-administered) but rarely 'co-addressed' and few co-use interventions exist. Young adulthood presents a key age for intervening in substance use, therefore understanding young adults' perspective is crucial, but little is known about how they understand or experience co-use. This study aimed to explore factors influencing co-use and changes to use within a population of young adults in the UK.

Methods: Participants were young adults recruited via three Further Education (vocational) colleges, who reported past 6-month co-use. Individual semi-structured interviews were carried out and analysed using the Framework approach.

Results: Eighteen participants were interviewed. Analysis identified influential factors, comprising three categories: (i) identity and social context including the concept of co-use; (ii) experiences; and (iii) understanding of effects. Family and peers were an important influence on use and cessation and young adults used their observation of peers' experiences to understand potential harms of each substance, as well as the complex relationship between cannabis use and mental health.

Discussion and conclusions: A broad range of factors influence co-use, and changes made to co-use, of tobacco and cannabis in young adults. Further investigation is needed to inform the development of co-use interventions. Credible co-use health risk information relevant to young adults, and the role of co-occurring mental health challenges need consideration in the development of co-use interventions.