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What are peptides?

Peptides are short chains of amino acids — the same building blocks that make up proteins, just far shorter. Where a protein might fold from hundreds of amino acids, a peptide is typically anywhere from 2 to 50. That short length is exactly what makes them useful: peptides act as precise signaling molecules, telling cells and tissues to do something specific — release a hormone, repair tissue, regulate appetite, trigger an immune response — without the broad, often unpredictable action of a small-molecule drug.

This isn't a fringe category. Insulin — the first peptide drug — has been in clinical use for over a century, and today more than 100 peptide-based therapeutics are approved for human use worldwide, spanning diabetes and obesity (GLP-1 drugs like semaglutide), oncology, bone density, growth hormone deficiency, and more. The "research peptides" covered in these guides are a separate, earlier-stage category: compounds with promising preclinical or early research data that are not approved as drugs and are sold strictly for laboratory research, not for human use.

Types of peptides

Research peptides are usually grouped by what they target or how they're believed to act. The categories below map directly onto the sections further down this page:

Final thoughts

Peptides sit in an interesting middle ground: small enough to be highly specific, large enough to do more than a typical pill. That's exactly why the field is moving fast, and why the gap between "promising early research" and "approved medicine" matters so much in this space. The guides below go compound by compound — what each one is studied for, where the EU legal line sits, and what to check on a Certificate of Analysis before trusting any vendor's claims. None of this is medical advice, and none of these compounds are intended for human or animal use outside an approved clinical context.