EncyclopediaUpdated April 2026

Peptide Encyclopedia

A catalog of 24 therapeutic peptides organized by mechanism. Each entry summarizes how the compound works, what the evidence shows, and current legal status. For the broader background on what peptide therapy is and how it works, see the peptide therapy guide.

The peptide regulatory landscape is changing. The FDA initiated a review in early 2026 that is expected to reclassify several Category 2 peptides — including BPC-157 and TB-500 — back into the legal compounding framework, restoring access for physicians and patients who lost it under the 2023 enforcement actions. The legal status shown for each entry below reflects current April 2026 state. For the authoritative running update on which peptides are reclassified and when, see are peptides legal?.

How to read this catalog: Each entry includes a short description of mechanism, the current legal status (Category 1 = currently compoundable, Category 2 = currently restricted, Pending / Investigational = not yet approved), and a link to the full encyclopedia entry with mechanism detail, clinical evidence, and access pathways.

Growth hormone secretagogues

Compounds that stimulate the pituitary to release growth hormone pulsatilely, mimicking endogenous patterns.

Healing & tissue repair

Peptides involved in soft-tissue recovery, angiogenesis, and skin health.

Weight management

GLP-1 agonists, triple agonists, and metabolic peptides under active research for obesity and metabolic disease.

Cognitive & neurological

Neuropeptides studied for focus, memory, anxiety modulation, and neuroprotection.

Immune & longevity

Peptides involved in immune modulation, thymic function, and longevity-related pathways.

Sexual wellness

Peptides that act on central pathways governing libido and sexual response.

Important context

Legal status changes. The peptide regulatory framework is genuinely fluid in 2026. The categories above reflect April 2026 state. Several restricted compounds are expected to return to Category 1 within months; conversely, additional enforcement actions could affect compounds currently available. The peptide legal status page is updated as regulatory developments occur.

Evidence quality varies. Some peptides have decades of human clinical trial data (Tesamorelin, PT-141). Others have promising mechanism studies and limited rigorous human evidence (BPC-157, MOTS-c). Some are derived primarily from Russian research that does not meet Western trial standards (Semax, Selank, Cerebrolysin, Epithalon). The encyclopedia entries flag evidence quality compound-by-compound rather than blurring it.

Access is physician-supervised.Therapeutic peptides for human use require a prescription from a licensed physician and preparation by a licensed compounding pharmacy. Grey- market “research chemical” sources are not safe access paths regardless of how they are marketed. See what happened to Peptide Sciences for context on the largest grey-market collapse and its aftermath.

Medical disclaimer

This encyclopedia is for informational purposes only and has not been clinically reviewed. It does not constitute medical advice. Always consult a licensed physician before considering any peptide therapy. Nuletic does not diagnose, treat, cure, or prevent any disease. Individual results vary. Meet our medical team.

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