  We collected and analyzed Instagram direct messages (DMs) from 173 youth aged
13-21 (including 86 LGBTQ+ youth). We examined youth's risk-flagged social
media trace data with their self-reported mental health outcomes to examine how
the differing online experiences of LGBTQ+ youth compare with their
heterosexual counterparts. We found that LGBTQ+ youth experienced significantly
more high-risk online interactions compared to heterosexual youth. LGBTQ+ youth
reported overall poorer mental health, with online harassment specifically
amplifying Self-Harm and Injury. LGBTQ+ youth's mental well-being linked
positively to sexual messages, unlike heterosexual youth. Qualitatively, we
found that most of the risk-flagged messages of LGBTQ+ youth were sexually
motivated; however, a silver lining was that they sought support for their
sexual identity from peers on the platform. The study highlights the importance
of tailored online safety and inclusive design for LGBTQ+ youth, with
implications for CHI community advancements in fostering a supportive online
environments.
