What are peptides, really?

What is a peptide?

A peptide is a short chain of amino acids linked by peptide bonds — essentially a small protein fragment. Peptides act as signaling molecules, telling cells to do things like release hormones, repair tissue, or regulate metabolism.

Main categories

• Metabolic / GLP-1 agonists — semaglutide, tirzepatide (prescription drugs).
• Growth-hormone secretagogues — e.g., ipamorelin (largely research/prescription).
• Repair & recovery peptides — studied for tissue support.
• Cosmetic peptides — e.g., copper peptides used topically in skincare.

Approved drug vs "research chemical"

This is the distinction that matters most. A peptide sold as a prescription drug has passed FDA review for safety and efficacy. A peptide sold "for research use only" has not — and selling or using those in humans is illegal. The label is not a loophole.

How to think about peptides

Match the claim to the evidence. Approved peptide drugs have large trials behind them. Many trendy peptides have only animal or early data. And legal supplements (like NAD+ precursors) are a separate, regulated category.

Frequently asked

Are peptides legal?

It depends. Approved peptide drugs are legal by prescription; dietary-supplement ingredients are legal as supplements; unapproved "research" injectables are not legal for human use.

Are peptides safe?

Approved peptide medications have established safety profiles under medical supervision. Unregulated sources carry real risks.

Sources

• U.S. FDA, guidance on peptide drug products.