Penn Analysis of Reddit Posts From About 7,800 Gray-Market Retatrutide Users Finds Fatigue, Appetite Swings, and Sleep Problems as Common as Nausea
University of Pennsylvania and Boston Children's Hospital researchers reported in a JAMA Network Open research letter on October 14, 2026 that they used large language models to read 148,640 retatrutide-related Reddit posts and comments from 27 communities, posted from 2021 to 2025, and mapped symptoms from 7,823 users who described current use of the unapproved drug. The most common terms were increased appetite (17.1%), fatigue (15.2%), increased energy (12.4%), nausea (11.6%), and insomnia (6.1%), and 4.8% mentioned a faster heart rate, a profile in which stomach symptoms were less dominant than in Lilly's trials. The authors called the findings hypothesis-generating, since what users injected, how much, and with what else cannot be verified.