Experiences of harm and mental ill-health among gay, bisexual and other men-who-have-sex-with-men who use methamphetamine or GHB/GBL in different combinations: findings from the COMeT study in Taiwan.

Introduction: Polydrug use in the context of chemsex is commonplace among gay, bisexual, and other men-who-have-sex-with-men (GBMSM). This study aimed to examine the differences in experiences of physical, social, and psychological harms, as well as mental ill-health among GBMSM who use different combinations of methamphetamine and gamma-hydroxybutyric acid/gamma-butyrolactone (GHB/GBL) during chemsex.

Method: Adult GBMSM participants who had experience of chemsex in the past 12 months participated in a cross-sectional online survey in Taiwan and self-reported their sociodemographic background, sexual behaviours, mental health, and experiences of harm following a chemsex session. We used univariable and multivariable logistic regression to assess the different experiences of harm and mental ill-health among GBMSM who engaged in chemsex without using methamphetamine, used methamphetamine but not GHB/GBL, and who used both drugs.

Results: Out of 510 participants who completed all items included in the analysis, 24.1% engaged in chemsex without using methamphetamine, 36.9% used methamphetamine but not GHB/GBL, and 39.0% used both drugs. Eighty five percent of men who used both methamphetamine and GHB/GBL reported at least one kind of social harm after a chemsex session, such as missing dates or appointments, or appearing "high" at work, followed by used methamphetamine but not GHB/GBL (69.7%) and those without using methamphetamine (37.4%). After controlling for polydrug and frequency of drug use in the multivariable logistic regression, those who used methamphetamine but not GHB/GBL and those who used both drugs were more likely to report experiencing physical and psychological harms compared to those who did not use methamphetamine (p < 0.003).

Conclusion: GBMSM who used both methamphetamine and GHB/GBL in a chemsex context were more likely to report experience of harms than those who only used a single chemsex drug or engaged in chemsex without methamphetamine or GHB/GBL. Harm reduction should focus on both preventing HIV and STI transmission and on minimising psychosocial harm to GBMSM, with varying impacts depending on drug use.