Feeling lonely in the online crowd: what TikTok tells us about young people and loneliness.

Loneliness is a pressing public health issue, with young people particularly affected. Given the widespread use of TikTok among younger demographics, the platform plays an influential role in shaping perceptions of health topics. This study examines the self-perceived causes and experiences of loneliness expressed by TikTok users. We built a dataset of the most popular, publicly available English-language TikTok videos globally that used the hashtag #lonely and performed a qualitative content analysis to assess (i) video tone, (ii) self-expressed identities related to loneliness, (iii) unmet desires expressed as the cause of loneliness, (iii) absences expressed as the cause of loneliness, and (v) changes in life circumstance as the cause of loneliness. The included videos (n = 184) generated over 687 million views. Absence (69.6%) was the prevailing theme of self-perceived causes of loneliness. This absence was mostly attributed to a lack of quality in a person's relationships (33.7%) or having no relationship (32.1%). Mental health (26.1%) was the most cited expression of identity related to the experience of loneliness. The overall sentiment of the videos was negative (83.2%). No videos were made by healthcare professionals or healthcare organizations offering health information or support. TikTok is an accessible, underutilized, and valuable data resource to understand the public portrayal and sentiment of pressing health topics in young people. Results reveal a prevalence of negatively toned videos, primarily expressing absence as a root cause of loneliness.