This dissertation presents the stories of women with chronic illnesses and their experiences communicating information about health and medicine on social media. To do this, this dissertation combines feminist theoretical and methodological approaches from the rhetoric of health and medicine and technical and professional communication to provide a nuanced understanding of this demographic’s experiences with medical knowledge-sharing and decision-making, as well as to make a case for the importance of conducting narrative-based research in clinical contexts. These findings are located within the context of biomedicine in order to contextualize how patients’ communication practices are shaped, constrained by, and in response to the dominant framework for medical care across the United States. This dissertation makes three primary arguments. First, I showcase how biomedical ideology exerts a powerful rhetorical force on beliefs about how healthcare knowledge should be developed, communicated, and taken up, often in ways that contribute to patient precarity. I situate this argument in a qualitative analysis of two threshold concepts at the center of the biomedical care framework—evidence and expertise—and demonstrate how participants grapple with and complicate these terms in the context of their own healthcare experiences. Next, I identify how the rise of health-related information on social media gestures to users’ strategic efforts to reframe effective healthcare delivery and communication as a systemic and collective concern, rather than an isolated and individual matter. Grounded in these findings, this project then extends Rebecca Walton, Kristen Moore, and Natasha Jones’ 4Rs heuristic—of recognizing, revealing, rejecting, and replacing systems of oppression and injustice—to articulate a vision of coalition-building in medical contexts. With participant insights regarding the goals for equitable healthcare practices and a range of actionable tips for patients, providers, caregivers, and allies alike, this dissertation ultimately provides a breadth of theoretical and practical resources for those working towards medical justice in their own online and offline communities.