High Rates of Drug Use and Chemsex Among PrEP Users and People with HIV in Milan Highlight Need for Targeted Interventions.

Chemsex, the use of psychostimulant substances during sexual activity particularly among men who have sex with men (MSM), is a growing public health concern. This study aimed to assess drug use, engagement in chemsex, and related knowledge among pre-exposure prophylaxis (PrEP) users and people with HIV (PWH) attending two sexually transmitted infection (STI) services in Milan, Italy. An anonymous online survey was conducted between January and March 2024 at a hospital-based clinic and a community-based center. The questionnaire explored demographics, HIV/PrEP status, drug use, chemsex, its disclosure to healthcare providers, and perceptions of drug use trends. Among 420 respondents, of whom 365 (84%) PrEP-users and 55 (13%) PWH, 167 (40%) reported current drug use and 68 (16%) engaging in chemsex. Polydrug use was also common (96/167, 57%). Commonly used substances included cocaine (50/167, 30%), mephedrone (45/167, 27%), 3,4-methylenedioxymethamphetamine (36/167, 22%), gamma-hydroxybutyrate/gamma-butyrolactone (33/167, 20%) and ketamine (29/167, 17%). The use of methylenedioxypyrovalerone (25/167, 15%) and crystal methamphetamine (10/167, 6%) was also consistent. Of the drug users, 62 (37%) did not disclose their substance use to healthcare providers, frequently citing lack of inquiry by clinicians or the perception that disclosure was not relevant. A total of 223/420 (53%) respondents knew people who used substances, and of these, 90.6% (202) perceived an increase in substance use within their community. In conclusion, the study revealed high rates of drug use and chemsex in Milan underscoring the need for increased healthcare provider awareness, and stigma-free environments to support risk reduction for chemsex users.