With the rapid increase of social media adoption globally, there has been a surge in the number of chronically ill adults who utilize social media tools as part of their illness management practice. While there have been numerous conceptual papers discussing the potential benefits of appropriation in this context, there seem to be limited studies that have explored the appropriation of social media platforms by this cohort. This paper addresses this gap in knowledge through a case study with a mixed methods approach to examine the appropriation of YouTube by chronically ill adults to better understand and manage their Fibromyalgia illness. Our results highlight the process of social media appropriation which include: viewing to vlogging; implementing workarounds and; borderless appropriation of social media tools. In addition, self-presentation, building transactive relationships, engagement in illness advocacy and technology features were found to influence appropriation outcomes for chronically ill adults on social media.