Catherine Varney Warns Unregulated Peptides Lack Human Safety and Efficacy

Unregulated gray-market peptide products heavily promoted on social media are not established to be safe or effective in humans and rely largely on animal studies. These alternative products have emerged as substitutes for FDA-approved therapies, but health experts warn that patients are acting on evidence that may not translate to humans while assuming all the risks of product quality assurance.

Animal Studies Drive Peptide Evidence

Approved glucagon-like peptide-1 (GLP-1) agents—such as liraglutide, semaglutide, and tirzepatide—underwent preclinical, animal, and human studies, and have been used for more than 20 years. In contrast, gray-market peptide products lack established safety or efficacy profiles in humans. Catherine Varney pointed to a scoping review published on August 11, 2026, in the American Journal of Sports Medicine, which revealed that 67% of peptide publications are preclinical and rely primarily on rats, yielding promising but variable results. Varney noted that only about 5% of animal-tested interventions ever reach regulatory approval. While some patients report feeling better after using these alternative products, long-term risks remain unknown because the existing human studies are largely uncontrolled and show only modest benefits at best.

Purity Testing Burdens Patients

Quality assurance for unregulated peptides falls completely on suppliers, leaving consumers exposed to significant purity discrepancies. Varney stated that third-party purity testing is rare and typically requires high health literacy and resources, noting an instance where a patient belongs to a group that pools money to test gray-market products. Independent analyses have found that peptides frequently contain only 5% to 75% of their labeled amount, falling far short of the 99% to 100% purity standards expected of a medication.