Fibromyalgia syndrome (FMS) is a chronic illness characterized primarily by widespread pain, fatigue, and sleep disturbances, although it is also associated with a wide variety of other symptoms such as cognitive dysfunction, nausea, and sensitivity to certain stimuli. Biomedical research has yet to find an organic cause for FMS. The lack of a clear biological etiology, combined with diagnostic difficulties and the condition’s association with certain psychological disorders, has generated controversy in the field over whether FMS is a “real” biomedical disorder with an organic cause or a condition that is primarily psychosocial. This controversy has high stakes for those diagnosed with FMS, who face significant stigma from both health care professionals and lay people. Through participant observation of FMS online support groups and social media platforms and semi-structured interviews with FMS patients and health care providers who treat FMS, this thesis explores how a variety of factors like mind-body dualism, the opioid epidemic, and gender may influence how FMS patients and physicians experience and respond to the ongoing controversy surrounding the condition. I also examine how social media and online support groups can be mobilized as sources of support, expression, and resistance against biomedical power, although based on how they are utilized they can produce both positive and negative effects on users.