OBJECTIVES Most social media (SM) sites have common terms and conditions dictating how data from the sites may be used, but how these relate to healthcare research is usually unclear. We analyzed studies included in two separate systematic literature reviews to assess whether researchers have evaluated the legal and ethical implications of using SM as a clinical tool or as a data source for healthcare research. METHODS In the first review, MEDLINE and Embase were searched (2008-2013) for articles evaluating the use of SM as a tool or application in healthcare. In the second review, MEDLINE and Embase were searched for English language studies on the use of SM in the context of adult vaccination. We assessed whether any of the individual studies considered the legal and ethical implications of using SM sources. RESULTS The first review identified 3,232 unique abstracts; 36 reported on interactive, internet-delivered programs, Facebook, and mobile apps, for improving health outcomes of patients with cancer, or inflammatory, mental health, musculoskeletal, neurologic, ophthalmologic, or sexual health-related disorders. The second review identified 1,264 publications, of which 32 used SM to communicate with patients, analyze content, or recruit patients for studies related to perceptions of adult vaccines. Among these 68 publications, no study reported whether the legal or ethical implications of using SM content were considered prior to conducting research. CONCLUSIONS The evidence suggests that legal and ethical implications of utilizing data from SM websites are not reported, and may not be considered, in current SM research. It is unclear whether this reflects the lack of clarity about what these restrictions mean for healthcare research, or whether researchers are not aware that such restrictions may exist. An informed debate to raise awareness of these issues and come to an understanding of the best way forward is urgently needed.