Sources: U.S. Food and Drug Administration (FDA) Compounding and the FDA (503A & 503B guidance) FDA warning letters on unapproved peptide products National Institutes of Health (NIH) PubMed Deep Dive: Regulatory Status of Popular Compounded Peptides Holt Law The science behind the peptide craze Scientific American The U.S. Food and Drug Administration is moving toward allowing compounding pharmacies to produce more than a dozen injectable peptides that were banned because of potentially significant safety risks, the New York The Human Lab Rats Injecting Themselves with Peptides Office for Science and Society McGill University