Penn AI Study Reveals Hidden Side Effects of Ozempic and Mounjaro Hidden in Reddit Posts

University of Pennsylvania researchers used AI to analyze more than 400,000 Reddit posts and identified patient-reported symptoms associated with GLP-1 drugs — the popular weight-loss and diabetes medications semaglutide and tirzepatide — that may not be fully captured in clinical trials or regulatory documents. The findings are shaking the world of pharmacology. The new study, published in Nature Health, covers more than half a decade of posts from nearly 70,000 Reddit users and highlights two main classes of symptoms that warrant further study: reproductive symptoms, including irregular menstrual cycles, and temperature-related complaints, such as chills and hot flashes. Fatigue ranked as the second most common complaint among Reddit users, despite reaching reporting thresholds in relatively few clinical trials. Clinical trials generally identify the most dangerous side effects of drugs, but they can fail to find what symptoms patients are most concerned about — and a large collection of social media posts may reflect those additional concerns. Researchers caution the findings are not conclusive. "We can't say that GLP-1s are actually causing these symptoms," the study's first author noted, adding that nearly 4% of Reddit users reported menstrual irregularities,  "a signal worth investigating." Ultimately, the researchers believe this kind of rapid, AI-assisted social media analysis could become a useful tool to spot early warning signs around emerging drugs, with patient discussions on platforms like Reddit and TikTok offering some of the earliest clues to real-world experiences. The authors are hoping to expand their research beyond Reddit to uncover further unreported symptoms.