Objectives: In this study, we investigated the relationships between a diagnosis of depression and anxiety disorder (DAD) and using online social media for healthcare. Online social media functions as a vital method of seeking health and disease information, providing low search costs and convenience for users. Because of these benefits, online social media can provide higher accessibility to people with mental health problems. Methods: We used propensity score matching to adjust for baseline differences and reduce confounding effects between DAD and non-DAD groups. Results: There was a statistically significant relationship between a diagnosis of DAD and the use of online social media. Conclusions: Patients with DAD are regarded as active and empowered decision-makers; social media functions as a vital method of seeking health and disease information, providing low search costs and convenience for users.