Chemsex in Australia: Prevalence, Psychosocial Correlates and Patterns of Polysubstance Use.

BACKGROUND: Chemsex is an increasingly recognized public health concern, remains inconsistently defined and often framed through risk-based perspectives. This cross-sectional survey (N = 401) examined chemsex engagement patterns and psychosocial correlates among gay, bisexual and other men who have sex with men in Australia. METHODS: We included demographic factors, substance use, chemsex engagement, perceptions of substances and psychosocial constructs. Descriptive statistics, bivariate analyses and logistic regression models were used to estimate associations between recent chemsex engagement and personal characteristics. RESULTS: Nearly 60% (59.9%) of participants reported lifetime chemsex engagement and 39.2% in the past three months. Demographic factors were not significant correlates. Psychosocial models explained modest variance, with higher drug-taking confidence associated with increased odds of recent chemsex engagement, and higher sex-positivity associated with lower odds. Participants' definitions of chemsex varied. Polysubstance use was common, with a mean of 2.9 (SD = 1.2) substances/session. Frequent co-use patterns included methamphetamine, gamma-hydroxybutyrate, and poppers. CONCLUSIONS: Chemsex was relatively common in this sample, with considerable variation in frequency of engagement, perceptions of which substances constitute chemsex, and patterns of substance use. Findings highlight definitional variability, limited explanatory power of individual-level correlates, and the importance of addressing polysubstance use in research and harm reduction.