Bridging the Prevention Divide: Chemsex, PrEP, and the Challenges of Comprehensive Sexual Health

This review examines the bidirectional relationship between chemsex and HIV pre-exposure prophylaxis (PrEP): chemsex practice among individuals engaged with PrEP, and PrEP awareness, willingness, and uptake among those who practice chemsex. We introduce the concept of a prevention divide, a persistent gap between elevated HIV/STI risk and sustained engagement with biomedical prevention, shaped by psychosocial, behavioural, and structural factors. Individuals who engage in chemsex, often characterized by polysubstance use, condomless sex, and multiple partners, frequently exhibit high risk for HIV and STI acquisition, yet this awareness does not consistently translate into preventive action. Despite elevated HIV vulnerability, barriers such as cost, poor mental health, and structural exclusion continue to hinder engagement with PrEP. Longitudinal and cross-sectional studies from Europe, Asia, North and South America confirm strong associations between chemsex and bacterial STIs, while also highlighting increased PrEP acceptability and adherence among high-risk subgroups. Yet, consistent with the disproportionate HIV burden among MSM, the existing literature remains largely centred on this population, leaving disaggregated data on heterosexuals, transgender people, sex workers, and migrants comparatively scarce. Across both directions, the gap is rarely one of motivation: chemsex users are frequently receptive to PrEP, and PrEP users who practice chemsex often engage strongly in the short term, but rather one of sustained structural support, as cost, fragmented services, and limited provider training determine whether prevention translates into durable protection. Integrated, person-centred care combining behavioural health, harm reduction, and social support is vital to closing this divide equitably.