Educational content only. Not medical advice, and no doctor-patient relationship is created. Read the medical disclaimer
THE PEPTIDE LIBRARY
36 entries, four quadrants, one honest grading system
Each entry tells you what a peptide is, how it is thought to work, what the human research actually shows, its U.S. regulatory status and where Youthful Medicine stands. We never publish doses.
I · Autoimmunity & Inflammation
II · Metabolic & Obesity Health
III · Hormonal Optimization
IV · Regenerative & Cellular Health
Tier:
Tier 1 · Prescribe today
Tier 2 · Prepare & watch
Tier 3 · Education only
QUADRANT I
Autoimmunity & Inflammation
Immune modulation, inflammatory tone and the gut barrier. Our most legally constrained quadrant, so expertise matters more than formulary.
Not a peptide · approved drug used off-label
Low-Dose Naltrexone (LDN)
An older medicine used at a fraction of its usual dose, studied for pain and inflammation in conditions like fibromyalgia.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Tripeptide · antioxidant
Glutathione
The body’s master antioxidant, a three-amino-acid peptide made in every cell.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Peptide
KPV
A three-amino-acid fragment of a natural anti-inflammatory hormone, studied for gut inflammation.
Tier 2 · Prepare & watch
Grade D · Preclinical only
Peptide
BPC-157
A synthetic peptide based on a stomach protein, widely discussed for gut and tissue healing.
Tier 2 · Prepare & watch
Grade C · Limited human evidence
Peptide
Thymosin Alpha-1
A thymus peptide that helps tune the immune system, approved abroad for hepatitis B and as a vaccine add-on.
Tier 3 · Education only
Grade B · Strong evidence, different label
QUADRANT II
Metabolic & Obesity Health
Incretin therapy, body composition and insulin sensitivity. Two approved anchors mean we can lead here today.
Peptide · GLP-1 receptor agonist
Semaglutide
A long-acting GLP-1 medicine that reduces appetite, improves blood sugar and lowers cardiovascular risk.
Tier 1 · Prescribe today
Grade A · Approved for this use
Peptide · GIP and GLP-1 receptor agonist
Tirzepatide
A dual-hormone medicine with the largest average weight loss of any approved obesity drug so far.
Tier 1 · Prescribe today
Grade A · Approved for this use
Peptide · GHRH analog
Tesamorelin
A growth-hormone-releasing hormone analog with proven effects on visceral (deep belly) fat.
Tier 1 · Prescribe today
Grade B · Strong evidence, different label
Not a peptide · amino acid derivative
Creatine
The best-studied supplement there is, and a quiet hero for protecting muscle during weight loss.
Tier 1 · Prescribe today
Grade B · Strong evidence, different label
Peptide · mitochondria-derived
MOTS-c
A small peptide encoded by mitochondrial DNA that acts like an exercise signal in animal studies.
Tier 2 · Prepare & watch
Grade D · Preclinical only
Peptide · growth hormone fragment
AOD-9604
A fragment of growth hormone once developed as an obesity drug. It did not work in human trials.
Tier 3 · Education only
Grade X · We decline
Peptide · GIP, GLP-1 and glucagon agonist
Retatrutide
A triple-hormone agonist in late-stage trials, with very large weight loss so far.
Tier 3 · Education only
Grade B · Strong evidence, different label
Peptides · investigational
Survodutide & Mazdutide
Two dual-agonist peptides being studied for obesity and fatty liver disease.
Tier 3 · Education only
Grade C · Limited human evidence
QUADRANT III
Hormonal Optimization
Axis preservation, pulsatility, sexual and bone health. The widest gap between what people ask for and what is lawful.
Peptide · GHRH analog
Sermorelin
A short GHRH analog that encourages your pituitary to release its own growth hormone in natural pulses.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Peptide · GnRH
Gonadorelin
A copy of the brain’s GnRH signal, used to help preserve natural testosterone and fertility signaling.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Peptide · melanocortin agonist
PT-141 (Bremelanotide)
A peptide that acts on desire in the brain rather than on blood flow.
Tier 1 · Prescribe today
Grade A · Approved for this use
Peptide · parathyroid hormone analog
Teriparatide
A parathyroid hormone peptide that builds new bone, and the clearest proof that rhythm matters.
Tier 1 · Prescribe today
Grade A · Approved for this use
Peptide hormone
Oxytocin
The “bonding hormone,” studied for social connection, stress and appetite, with disappointing large trials.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Glycoprotein hormone (larger than a peptide)
hCG
A hormone that mimics LH, used to support natural testosterone and fertility signaling.
Tier 1 · Prescribe today
Grade B · Strong evidence, different label
Peptides · GH secretagogues
Ipamorelin & CJC-1295
The most-requested growth hormone combination, currently education-only in the U.S.
Tier 3 · Education only
Grade D · Preclinical only
Peptide
Kisspeptin-10
The master switch above GnRH, studied in fertility research.
Tier 3 · Education only
Grade C · Limited human evidence
Peptide · GH secretagogue
Hexarelin
A potent growth hormone secretagogue studied mainly in research settings.
Tier 3 · Education only
Grade D · Preclinical only
QUADRANT IV
Regenerative & Cellular Health
Three sub-pillars: Cellular Energy, Structural Repair, and Neural & Recovery. The widest quadrant with the thinnest Tier 1.
Peptide · mitochondria-targeted
SS-31 (Elamipretide)
The first FDA-approved mitochondria-targeted drug, approved for one rare disease.
Tier 3 · Education only
Grade C · Limited human evidence
Peptide · mitochondria-derived
Humanin
A mitochondria-derived peptide linked to cell survival in laboratory research.
Tier 3 · Education only
Grade D · Preclinical only
Not a peptide · coenzyme
NAD+
A coenzyme every cell needs for energy and DNA repair. Levels fall with age.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Peptide
TB-500
A fragment of thymosin beta-4, studied for wound and soft-tissue healing.
Tier 2 · Prepare & watch
Grade D · Preclinical only
Peptide · copper complex
GHK-Cu
A copper-binding peptide found in blood that supports skin repair and collagen.
Tier 1 · Prescribe today
Grade C · Limited human evidence
Peptide · IGF-1 splice variant
MGF & PEG-MGF
Splice variants of IGF-1 linked to muscle repair in research.
Tier 3 · Education only
Grade D · Preclinical only
Peptide · BPC-157 analog
Pentadeca Arginate (PDA)
A BPC-157 look-alike that appeared after BPC-157 compounding was restricted.
Tier 3 · Education only
Grade D · Preclinical only
Peptide · EPO-derived
ARA-290 (Cibinetide)
An erythropoietin-derived peptide studied for nerve pain, without EPO’s effect on red blood cells.
Tier 3 · Education only
Grade C · Limited human evidence
Peptide · nasal
Semax
A nasal peptide developed in Russia for stroke recovery and cognition.
Tier 2 · Prepare & watch
Grade C · Limited human evidence
Peptide · nasal
Selank
A Russian nasal peptide studied for anxiety.
Tier 3 · Education only
Grade C · Limited human evidence
Peptide
DSIP
A 1970s “sleep peptide” whose human sleep benefits have not held up.
Tier 3 · Education only
Grade D · Preclinical only
Peptide · bioregulator
Epitalon
A four-amino-acid peptide from Russian research on the pineal gland and aging.
Tier 2 · Prepare & watch
Grade C · Limited human evidence
Peptide-like small molecule
Dihexa
A brain-targeted molecule marketed for memory, with only animal data and a plausible safety concern.
Tier 3 · Education only
Grade X · We decline
Short peptides · one research program
Bioregulator Peptides
Five short peptides from one Russian research program, claimed to act on specific organs.
Tier 3 · Education only
Grade D · Preclinical only