Peptide Nomenclature
Carnosine and retatrutide are both peptides. So are insulin, oxytocin, and BPC-157. The word “peptide” tells you almost nothing about mechanism, evidence, or regulatory status. The field needs a working vocabulary.
The Peptide Association proposes a 12-category functional classification system to give this category a shared framework — organized by mechanism, not by marketing. Each category carries an evidence grade, a regulatory summary, and links to the compounds within it.
The 12 functional categories
Click any category to read the full definition, mechanism, regulatory status, evidence assessment, and compound list.
Metabolic GLP-Axis
Incretin and amylin mimetics targeting appetite, insulin, and body weight
Regenerative / NO-Receptor
Tissue repair and angiogenesis via nitric oxide and growth factor pathways
Thymic & Immune
Thymic hormone mimetics that regulate T-cell maturation and immune function
Bio-Regulators
Ultra-short tissue-targeted peptides that modulate gene expression and aging
GH Secretagogues
GHRH analogs and ghrelin mimetics that stimulate pituitary GH release
Growth Hormone
Direct GH receptor agonism via recombinant hGH and synthetic GH fragments
Cosmetic & Dermatologic
Skin repair, collagen synthesis, and anti-inflammatory dermatologic peptides
Nootropic & CNS
Neuropeptides targeting BDNF, anxiety, cognitive function, and neuroregeneration
Mitochondrial
Mitochondrially-encoded peptides targeting energy metabolism and cellular aging
Sexual Function
Central melanocortin and hypothalamic peptides for libido and sexual response
Visceral & Metabolic
Targeted visceral adiposity reduction via GH-axis and NNMT pathway modulation
Sleep & Circadian
Peptides that regulate sleep architecture, melatonin, and circadian entrainment
Evidence tiers
Strong = large RCTs and/or FDA approval for a relevant indication. Moderate = clinical trial evidence without full FDA approval, or approved in 10+ countries. Limited = primarily preclinical data or small human studies. Emerging = early-stage human data, mechanistic rationale, or novel compounds in active development.
How to use this framework
This taxonomy is a reference tool, not a prescription guide. Here is how practitioners and patients get the most from it.
Start with the category, not the compound
Before researching a specific peptide, identify which functional category it belongs to. This tells you the mechanism, evidence grade, and regulatory environment before you read a single study.
Use evidence grades as a prior
Strong evidence categories (GLP-axis, Growth Hormone, PT-141) have RCT data and FDA approvals. Emerging categories (Mitochondrial, Sleep-Circadian) have compelling science but limited human trials. Grade your confidence accordingly.
Cross-category compounds are common
Tesamorelin appears in both GH Secretagogues and Visceral-Metabolic. Epitalon appears in Bio-Regulators and Sleep-Circadian. When a compound serves multiple functions, check both category pages.
Regulatory status shifts
BPC-157 compounding was affected by 2023 FDA guidance. Semaglutide compounding was restricted as supply normalized. Each category page reflects current status — verify with a licensed provider before clinical use.
Ready to discuss a specific protocol?
Understanding the taxonomy is the first step. A peptide-literate physician can translate categories into a personalized protocol based on your labs, goals, and health history.
Find a verified providerThis taxonomy is an educational framework, not medical advice. Consult a qualified physician before considering any peptide therapy. Regulatory status of individual compounds changes — verify current status with a licensed provider.