The popularity of ADHD-related social media content has raised concerns about self-diagnosis. Based on the SESAM model, which suggests that selective exposure to health-related media increases the salience of related health goals, this study examines the relationship between exposure to adult ADHD content on social media and self-diagnosis of the condition. An experiment using Instagram-like stimuli, some mentioning ADHD and some not, tested whether exposure to ADHD-related content influenced self-diagnosis among participants who had and had not previously self-diagnosed with ADHD. The mediating role of social comparison was also examined. Results showed that exposure to ADHD-related content increased post-exposure self-diagnosis scores among participants who had already self-diagnosed before exposure. No effect was found among participants without prior self-diagnosis. Social comparison did not mediate the relationship. However, it was a strong predictor of self-diagnosis.