BackgroundWe assessed the association between sexualized drug use (SDU), and incident sexually transmitted diseases (STDs) and human immunodeficiency virus (HIV) infections among men who have sex with men (MSM).MethodsWe used data from the MS2 cohort study, conducted at the STI Outpatient Clinic of the Public Health Service of Amsterdam, the Netherlands, in 2014–2019. Eligible participants were adult HIV-negative MSM with ≥2 STDs in the preceding year and MSM living with HIV and ≥1 STD. Participation encompassed 3-monthly visits including STD screening and questionnaires on drug use. Primary outcomes were incident HIV, anal chlamydia/gonorrhoea, and syphilis. We studied the association between SDU of individual drugs and incident HIV and STDs, using Poisson regression. Analyses were adjusted for age and HIV-status.Results131 HIV-negative MSM and 173 MSM living with HIV were included for analysis. SDU with GHB/GBL (aIRR = 7.2, 95% CI = 1.4–35.5) in the 3 months before testing was associated with incident HIV. ...