The major peptide categories

To make a peptide library navigable, peptides have to be grouped somehow. The organizing principle we use on this site is the system each peptide acts on and the research question it has been studied to answer. Here’s a tour of those categories and what to expect from each.

Metabolic peptides

These are peptides that influence glucose handling, appetite, and energy metabolism — most prominently the incretin family (GLP-1, GIP) and their synthetic analogs. Semaglutide and tirzepatide are the best-studied examples, and also the best-evidenced peptides in any category. Both are FDA-approved, have run through Phase 3 programs for diabetes and weight management, and have follow-on cardiovascular outcomes data.

What to expect from the evidence: robust, industry-funded trials with large patient numbers, clear clinical endpoints, and active post-market surveillance. The debates are about long-term effects, regulatory supply, and who can access them safely.

Healing and recovery

Peptides in this category are studied for effects on tissue repair, wound healing, tendon and ligament regeneration, and inflammation modulation. BPC-157 and TB-500 (a fragment of thymosin β4) are the most-discussed members.

What to expect from the evidence: nearly entirely preclinical. Most data come from rodent models, and the body of work is heavily concentrated in a small number of laboratories. These compounds are not FDA-approved, and the gap between the rodent literature and what commercial vendors claim is substantial.

Growth-hormone-related peptides

This category includes growth hormone–releasing hormone analogs (sermorelin, CJC-1295) and growth hormone secretagogues (ipamorelin, GHRPs). They act on the pituitary to stimulate GH release, preserving the pulsatile feedback biology rather than introducing exogenous GH.

What to expect from the evidence: a mixture. Sermorelin has a historical FDA indication (now withdrawn from the US branded market). Others reached Phase 2/3 stages before being discontinued. Mechanism is well-characterized; long-term outcome data at the doses used in grey markets are scarce. All are on the WADA Prohibited List.

Cognitive peptides

This is the most geographically lopsided category. Semax and Selank, developed in Russia, are registered pharmaceuticals in that country and essentially unknown to Western regulators. Cerebrolysin is an Austrian-registered porcine brain extract with decades of mixed evidence in stroke and dementia.

What to expect from the evidence: large Russian-language clinical literature of variable methodology, sparse English-language peer-reviewed replication, and no FDA-approved status for any of these in the United States.

Longevity and metabolic-aging peptides

This is the newest and most speculative category. NAD+ (actually a coenzyme, not a peptide), 5-Amino-1MQ (a small molecule NNMT inhibitor, also not a peptide), and MOTS-c (a genuine mitochondrial-derived peptide) fall here. They are grouped because they are marketed together in the longevity-wellness space.

What to expect from the evidence: primarily preclinical, with a growing body of early human data for oral NAD+ precursors. Claims about “anti-aging” effects in humans rest on extrapolation, not Phase 3 outcome trials.

Blends

Blends — KLOW, GLO, and others — are not research compounds but vendor-coined product formulations combining several individual peptides. Their constituents vary between sellers. No peer-reviewed pharmacology exists on any blend as a unit; only on its individual components, studied separately.

What to expect from the evidence: none directly. Reading a blend’s marketing is, strictly, reading claims derived from research on its individual components — combined and extrapolated in ways the original studies don’t support.

What unites the list

Peptides look like a single category because they share a biochemistry (amino acid chains, often bound to specific receptors). In practice, this site covers several very different things: approved pharmaceuticals with Phase 3 data, discontinued pharmaceutical programs, preclinical research compounds, foreign-approved drugs, and vendor marketing labels. Keeping those categories distinct is the first step in reading peptide information carefully.