What are people saying about DoxyPEP? A topic-based analysis of Reddit discussions

BACKGROUND: Doxycycline post-exposure prophylaxis (DoxyPEP) is a strategy for bacterial STIs prevention; however, despite strong evidence from clinical trials that DoxyPEP reduces the incidence of syphilis and chlamydia, its real-world uptake is shaped by public perception. In this study, we aim to examine how DoxyPEP is discussed in online communities and identify dominant themes that may influence its implementation. METHODS: We applied an unsupervised text analysis approach (BERTopic) to identify interpretable themes from a large corpus of Reddit posts discussing DoxyPEP posted between November 2020 and May 2025, and subsequently conducted expert-informed interpretation to refine the thematic structure. RESULTS: We identified 8139 posts for topic modelling, of which 5296 were assigned to interpretable topics. Discussions encompassed prevention strategies, sexual practices, antimicrobial resistance and healthcare access. Notably, conversations extended beyond men who have sex with men contexts to include heterosexual, polyamorous and swinger communities, where DoxyPEP was discussed as part of broader risk management practices. Rather than simple misinformation, posts reflected active negotiation of evolving biomedical evidence and personal risk. Access to LGBTIQA+-friendly clinicians and telehealth services facilitated uptake, whereas provider knowledge gaps acted as barriers. CONCLUSION: Online community-generated discourse provides insight into how STIs prevention strategies and interventions are interpreted in practice, particularly around risk assessment, access to appropriate care and concerns about antimicrobial resistance. Clearer, consistent clinical guidance and information-sharing by community-level organisations may help support informed and equitable DoxyPEP implementation and better sexual health education.