Understanding Health-Related Discussions on Reddit: Development of a Topic Assignment Method and Exploratory Analysis
Authors: Chan Garrett J , Fung Mark , Warrington Jill , Nowak Sarah A 
Published: January 2025

Background
Social media has become a widely used way for people to share opinions about health care and medical topics. Social media data can be leveraged to understand patient concerns and provide insight into why patients may turn to the internet instead of the health care system for health advice.

Objective
This study aimed to develop a method to investigate Reddit posts discussing health-related conditions. Our goal was to characterize these topics and identify trends in these social media–based medical discussions.

Methods
Using an initial query, we collected 1 year of Reddit posts containing the phrases “get tested” and “get checked.” These posts were manually reviewed, and subreddits containing irrelevant posts were excluded from analysis. This selection of posts was manually read by the investigators to categorize posts into topics. A script was developed to automatically assign topics to additional posts based on keywords. Topic and keyword selections were refined based on manual review for more accurate topic assignment. Topic assignment was then performed on the entire 1-year Reddit dataset containing 347,130 posts. Related topics were grouped into broader medical disciplines. Analysis of the topic assignments was then conducted to assess condition and medical topic frequencies in medical condition–focused subreddits and general subreddits.

Results
We created an automated algorithm to assign medical topics to Reddit posts. By iterating through multiple rounds of topic assignment, we improved the accuracy of the algorithm. Ultimately, this algorithm created 82 topics sorted into 17 broader medical disciplines. Of all topics, sexually transmitted infections (STIs), eye disorders, anxiety, and pregnancy had the highest post frequency overall. STIs comprised 7.44% (5876/78,980) of posts, and anxiety comprised 5.43% (4289/78,980) of posts. A total of 34% (28/82) of the topics comprised 80% (63,184/78,980) of all posts. Of the medical disciplines, those with the most posts were psychiatry and mental health; genitourinary and reproductive health; infectious diseases; and endocrinology, nutrition, and metabolism. Psychiatry and mental health comprised 26.6% (21,009/78,980) of posts, and genitourinary and reproductive health comprised 13.6% (10,741/78,980) of posts. Overall, most posts were also classified under these 4 medical disciplines. During analysis, subreddits were also classified as general if they did not focus on a specific health issue and topic-specific if they discussed a specific medical issue. Topics that appeared most frequently in the top 5 in general subreddits included addiction and drug anxiety, attention-deficit/hyperactivity disorder, abuse, and STIs. In topic-specific subreddits, most posts were found to discuss the topic of that subreddit.

Conclusions
Certain health topics and medical disciplines are predominant on Reddit. These include topics such as STIs, eye disorders, anxiety, and pregnancy. Most posts were classified under the medical disciplines of psychiatry and mental health, as well as genitourinary and reproductive health.