Chemsex Practice Among PrEP Users in Buenos Aires, Argentina

Chemsex, defined as the intentional use of psychoactive substances to enhance sexual activity, has been associated with a higher frequency of sexually transmitted infections (STIs) diagnosis among HIV pre-exposure prophylaxis (PrEP) users. Evidence from Latin America remains limited. This research aims to characterize the practice of chemsex and STIs prevalence in PrEP users in Buenos Aires, Argentina. We conducted a descriptive, cross-sectional study using clinical records and a self-administered ad-hoc questionnaire among PrEP users attending four public hospitals. Between February to October 2024, 165 PrEP users were included. The prevalence of chemsex, during the previous year, was 32%. The drugs used, in order of frequency, were MDMA 21%; cocaine 14%; gamma-hydroxybutyrate 12%; ketamine 10%; methamphetamine 6%; mephedrone 2%; and gamma-butyrolactone 1%. Additionally, 48% reported concurrent use of two or more drugs during the practice. A multivariate logistic regression analysis showed that engaging in chemsex was significantly associated with higher odds of reporting an STI in the past year [aOR 3.67 (95% CI 1.67 - 8.42) p 0.001). Age, time on PrEP, number of sexual partners, and engagement in group sex were not independently associated with STI diagnosis. In conclusion, chemsex was common among PrEP users in Buenos Aires and independently associated with recent STI diagnosis, highlighting the importance of integrating behavioral assessments and harm reduction strategies into PrEP and sexual health policymaking.