I argue that the recurring practice of self-diagnosis of psychiatric conditions such as autism spectrum disorder and attention-deficit/hyperactivity disorder on social media platforms poses a threat to personal autonomy understood as self-governance. My main argument is that self-diagnosis conducted without professional expertise is prone to lead to misdiagnosis, which can take the form of a distortion of self-image. This may result in pathologizing normal experiences and behaviors and the adoption of behavioral adjustments that harm those who engage in self-diagnosis. Acknowledging (...) that the surge of self-diagnosis content is a response to inadequacies of mental health care systems in many parts of the world, I argue against prohibiting such content and end with a more modest suggestion of implementing warnings alongside it on social media platforms, as is already common practice for misinformation content on diseases like Covid-19. (shrink)