Penn Researchers Used AI to Find Unreported GLP-1 Side Effects in 400,000 Reddit Posts
Krissy Vann | Host, All Things Fitness and Wellness
Millions of people are taking GLP-1 medications, and a growing number of them are talking about it online. Researchers at the University of Pennsylvania decided to listen. Using artificial intelligence to analyze more than 400,000 Reddit posts from nearly 70,000 users, Penn's School of Engineering and Applied Science identified patient-reported symptoms associated with semaglutide and tirzepatide that may not be adequately captured in clinical trials or regulatory filings. The findings were published in Nature Health.
The study spans more than five years of posts and flags two categories of symptoms researchers believe warrant further clinical attention: reproductive symptoms, including irregular menstrual cycles, and temperature-related complaints such as chills and hot flashes.
The research team was careful to frame the findings as signals rather than conclusions. The study does not establish causation, and the authors acknowledge that social media data is not a representative sample. Still, the volume is notable. Nearly 4% of Reddit users in the sample reported menstrual irregularities, a figure the researchers say would be even higher in a female-only sample. First author and doctoral student Neil Sehgal called it "a signal worth investigating."
Known side effects like nausea also surfaced prominently, which senior author Sharath Chandra Guntuku cited as evidence the methodology is sound. The underreported symptoms, he noted, "came from patients themselves, unprompted," making them potentially useful leads for clinicians. Co-author Lyle Ungar pointed to a structural limitation of trials: they are designed to catch dangerous side effects, but often miss "what symptoms patients are most concerned about."
For the fitness and wellness industry, where GLP-1 use among clients and members has grown substantially, the findings add context to a drug class operators are already navigating. Reproductive symptoms and temperature dysregulation are the kinds of issues that surface in group fitness settings, and coaches or instructors working with GLP-1 users may encounter them without a clear clinical framework to reference.
The Penn team has indicated the methodology could be extended to other drug classes and platforms as a way to surface leads for further clinical investigation.
