Unreported GLP‑1 effects

Glucagon-like peptide-1 drugs are medicines that help people feel full and eat less, and a new Nature Health study says patient posts suggest some side effects may be missing from the usual lists. (nature.com) University of Pennsylvania researchers analyzed 410,198 Reddit posts written from May 2019 through June 2025 about semaglutide and tirzepatide. They identified 67,008 users who said they took the drugs, and 43.5% described at least one side effect. (nature.com) The most common complaints in the dataset were gastrointestinal problems already linked to these drugs, including nausea in 36.9% of users who reported side effects, fatigue in 16.7%, vomiting in 16.3%, constipation in 15.3%, and diarrhea in 12.6%. (nature.com) The new signals were reproductive and temperature-related symptoms that the paper says are not well captured in current labeling or trials. The researchers highlighted menstrual irregularities, chills, and hot flashes, and said nearly 4% of users in the sample reported menstrual changes. (nature.com, seas.upenn.edu) These drugs are already widely used for obesity and diabetes, so researchers are looking for problems that may show up after approval, in everyday use, rather than in tightly run trials. The Nature Health paper says large-scale social media analysis can complement standard drug-safety monitoring by surfacing emerging signals from patients themselves. (nature.com) The study used artificial intelligence to translate informal Reddit posts into standardized medical symptom terms and then compare those reports with drug labels and trial records. Senior author Sharath Chandra Guntuku said the method picked up known effects such as nausea, which the team took as evidence that the system was finding real patterns. (seas.upenn.edu) The authors also drew a line between a signal and proof. First author Neil Sehgal said the study cannot show that glucagon-like peptide-1 drugs caused the symptoms, because Reddit posts are anonymous self-reports and are not clinical diagnoses. (seas.upenn.edu) Current United States prescribing information already lists many gastrointestinal reactions for these medicines, and the Food and Drug Administration label for Zepbound also lists fatigue among common adverse reactions. The newly flagged menstrual and temperature-related complaints are the gaps the Penn team says deserve follow-up in formal studies. (accessdata.fda.gov, nature.com) The paper lands as doctors and regulators are still sorting out the real-world safety profile of drugs that moved from diabetes treatment into mass use for weight loss. The researchers said patient forums can work like an early warning system, but only if the signals are checked against clinical data next. (seas.upenn.edu, nature.com)