Verbal authenticity is the degree to which a person is monitoring self-expression that reflects one’s motivation. Though benefits of authentic expression are studied in interpersonal, social, and entrepreneurial success, few have explored authenticity within online health communities for social support and self-disclosure, especially when the health issues are stigmatized offline, such as living with chronic pain and opioid use. Given the health benefits authentic expression provides, the present study explored the discourse of pain management prevalent on Reddit.com and investigated the authentic expression patterns across its labeled communities: subreddits. Relevant messages (N = 57, 564) from posts and replies were collected and evaluated using the authenticity category developed by the Linguistic Inquiry and Word Count (LIWC) software. The analysis suggests that subreddits built for inviting inquiries such as “r/AskReddit” “r/AskDocs” had higher scores in terms of authentic expression, while others like “r/politics” “r/marvelstudios” had lower authenticity. Also, the more frequently a user posts and replies in a community, the more likely they expressed authentically for the post construction, but not for the reply authenticity. This study explicates the concept of authenticity by exploring what authentic expression means for health benefits in pain management. It also contributes to a growing body of studies focusing on the therapeutic effect of authentic expression in online health communities.