Objective To understand how the emerging public health issue of chemsex relates to broader patterns of sexualised drug use (SDU) among men who have sex with men (MSM), which has been understudied.

Methods Potential participants were invited to take part in an anonymous, cross-sectional online survey through Facebook advertising and community organisations’ social media posts (April–June 2018). Multivariable logistic regression was used to compare MSM who engaged in recent SDU (past 12 months) with those who did not, and those who engaged in chemsex (γ-hydroxybutyrate/γ-butyrolactone, crystal methamphetamine, mephedrone, ketamine) with those who engaged in other SDU (eg, poppers, cocaine, cannabis).

Results Of the 1648 MSM included, 41% reported recent SDU; 15% of these (6% of total, n=99) reported chemsex. Factors associated with SDU were recent STI diagnosis (aOR=2.44, 95% CI 1.58 to 3.76), sexual health clinic attendance (aOR=2.46, 95% CI 1.90 to 3.20), image and performance-enhancing drug use (aOR=3.82, 95% CI 1.87 to 7.82), greater number of condomless anal male partners, lower satisfaction with life and greater sexual satisfaction. Predictors of chemsex compared with other SDU were not being UK-born (aOR=2.02, 95% CI 1.05 to 3.86), living in a densely populated area (aOR=2.69, 95% CI 1.26 to 5.74), low sexual self-efficacy (aOR=4.52, 95% CI 2.18 to 9.40) and greater number of condomless anal male partners. Living with HIV, taking pre-exposure prophylaxis (PrEP), and experiencing or being unsure of experiencing sexual contact without consent were significantly associated with SDU and chemsex in bivariate analyses but not in the multivariable.

Conclusion Health and behavioural differences were observed between MSM engaging in chemsex, those engaging in SDU and those engaging in neither. While some MSM engaging in chemsex and SDU appeared content with these behaviours, the association with life satisfaction and sexual self-efficacy indicates psychosocial support is needed for some. The association with sexual risk and sexual consent also indicates the importance of promoting harm reduction among this population (eg, condoms, PrEP, drug knowledge).