A legal loophole allows consumers to purchase peptide semaglutide without a prescription, but websites that sell them do not sell supplies or provide guidance. We assessed the ability and confidence of college students at the University of Connecticut and older adults in performing the required steps from September 1, 2025, through January 30, 2026. Participants looked up information online. We provided various semaglutide and diluent vials and supplies. We assessed 34 steps in the process and assigned 1 point for each step successfully completed. We rated confidence on a scale from 1 (no confidence) to 5 (complete confidence). We evaluated 20 adults aged ≥18 years (12 male, 8 female) with a mean (SD) age of 40 (21) years. Participants completed 15 of the 34 steps correctly (mean [SD] = 44% [50%]). We found errors that could result in incorrect dosing, needle sticks, or infections. Mean (SD) confidence was low before and after the demonstration but not significantly so (2.3 [0.7] vs 1.9 [1.0]; P = .19). Untrained adults without experience injecting medications could be at high risk of adverse events when they try to self-administer grey market peptide semaglutide products using only internet information. Future studies should assess a larger and more diverse population and determine whether the results are similar with other products sold as peptides without a prescription.
