Background <p>Caregivers’ health is a crucial public health concern. Although breast cancer’s psychosocial burden extends to offspring caregivers, their trauma narratives and seeking of social support remain understudied, particularly in China. This study aimed to explore how adult offspring caregivers share trauma stories in online support groups (OSGs) and identify how narrative practices may facilitate self-healing.</p> Methods <p>We employed a mixed qualitative study approach – using large language models and thematic analysis to examine offspring caregivers’ sentiment patterns and narrative characteristics at different treatment stages for the parent for whom they were caring. The sample comprised 705 posts and comments from offspring of breast cancer patients, collected from the Douban OSG “Having a Breast Cancer Patient in My Family.”</p> Results <p>At the early stage of treatment, most offspring caregivers of breast cancer patients exhibited negative sentiments. A combination of positive, negative, and neutral sentiments was observed in the middle stage. In the late stage, positive sentiments predominated. Furthermore, we identified three narrative themes aligning with sentiment trajectories among offspring caregivers: collapse, interactive, and constructive narratives. These findings suggest the self-healing function of media-based narratives. We argue that the deeper exploration of online trauma narratives related to breast cancer is necessary for more effectively conceptualizing the role of OSGs in providing health-related support.</p> Conclusions <p>Trauma narration of offspring caregivers, particularly in online spaces, is an underexplored, but potentially crucial area. Our study revealed the role of the OSG impact on individual emotional and behavioral experiences that could be integrated into interventions to enhance psychological treatments.</p>