Chemsex and its impact on gay and bisexual men who have sex with men: Findings from an online survey in Belgium (2025)

OBJECTIVES: The study aimed to estimate the prevalence of sexualized drug use, or chemsex, in a wide group of gay, bisexual and other men who have sex with men (gbMSM) in Belgium. It examined which drugs gbMSM used before and during sex, the frequency with which they used it, whether they experienced non-consensual sex, and evaluated the impact of chemsex on the health and professional and social lives of respondents.
METHODS: We conducted an online survey among Belgian gbMSM. Five specific questions on chemsex were included in the survey. These questions assessed whether gbMSM engaged in chemsex. If they did, they were asked to provide information on which drugs they had used and how often. We asked whether their and their partners' boundaries had been respected and whether and how engaging in chemsex had affected a range of life domains.
RESULTS: Of 836 respondents, 258 (30.9%) self-reported having had sex under the influence of substances ("chemsex") in the previous 6 months. Of these, 227 (88%) were considered chemsex users according to the definition used for the analysis. Poppers (73%), gamma-hydroxybutyrate/gamma-butyrolactone (GHB/GBL; 69%) and cathinones (68%) were the most commonly reported substances. Almost half of respondents (45%) engaging in chemsex were high on drugs during at least half of their sexual encounters. Nearly 1 in 10 (9%) reported that boundaries had not been respected, suggesting non-consensual sexual activities. The 82 respondents experiencing negative impacts from their chemsex use reported that mental health (65%), physical health (40%) and sexual health (38%) were most impacted.
DISCUSSION: Our findings provide a snapshot of the current chemsex situation in Belgium. The frequency of chemsex is concerning because several health, professional and social aspects are impacted. Almost 1 in 10 respondents using chemsex reported that chemsex impacted consent around sex, requiring additional efforts to eradicate these non-consensual sexual experiences. Therefore, larger scale research focusing on respected boundaries and consent during chemsex and the frequency of drug use for sex seems required. Additionally, sensitisation, as well as care and support programmes are critical. [Author's abstract]