Self-diagnosis is the process of diagnosing, or identifying, medical conditions in oneself. It may be assisted by medical dictionaries, books, resources on the Internet, past personal experiences, or recognizing symptoms or medical signs of a condition that a family member previously had.

Depending on the nature of an individual's condition and the accuracy of the information they access, self-diagnoses can vary greatly in their safety. Due to self-diagnoses' varied accuracy, public attitudes toward self-diagnosis include denials of its legitimacy and applause of its ability to promote healthcare access and allow for individuals to find solidarity and support. Furthermore, external influences such as marketing, social media trends, societal stigma around disease, and to which demographic population one belongs greatly affect the use of self-diagnosis.