A Chatbot to Reduce Chemsex and HIV-related Risk Behaviors Among Men Who Have Sex With Men

The goal of this clinical trial is to investigate whether receiving chatbot-delivered stage-of-change-tailored online interventions is effective in reducing chemsex among men who have sex with men in Hong Kong. The main question it aims to answer is: Does chatbot-delivered stage-of-changed online interventions reduce chemsex among men who have sex with men Eligible participants will be randomly assigned to either the intervention or the control group. The control group will watch one online video introducing chemsex-related knowledge and harm reduction skills per week for 12 weeks. On top of the interventions received by the control group, participants in the intervention group will have access to a chatbot during the 12-week intervention period. The chatbot will deliver 12 weekly episodes of interventions tailored to once's current stage-of-change related to chemsex. The chatbot will also address questions related to chemsex during the intervention period.

Inclusion Criteria: * Hong Kong men aged at least 18 years * Able to understand Cantonese * Had anal intercourse with at least one man within the past six months * Willingness to provide contact information for follow-up * Having access to WhatsApp Exclusion Criteria: * Self-reported a diagnosis of schizophrenia or bipolar disorder