The Research-Peptide Directory: Every Peptide, Organized
A map of the whole peptide field: growth-hormone secretagogues, healing peptides, longevity and mitochondrial peptides, cosmetic peptides, each linked to a plain-English, evidence-first breakdown.
“Peptides” gets used as if it named a single category of thing. It doesn’t. The word covers everything from insulin and the GLP-1 drugs, among the most-studied medicines on earth, to research chemicals sold online with nothing but animal data and forum anecdotes behind them. This directory is the map: every peptide we cover, grouped by what it’s actually for, each linked to a plain-English breakdown of what the evidence does and doesn’t support.
The single most useful skill in this field is placing any given peptide on the evidence spectrum: approved drug, promising-but-preliminary, or hype, before you engage with the claims. Use this directory to find where each one sits.
If you’re brand new, start with The Beginner’s Guide to Peptides, then come back here to go deep.
Start here: the foundations
How peptides work at all: the concepts that make every entry below readable.
- The Difference Between Peptides and Proteins, Explained
- How Peptides Signal: Receptors, Cascades, and Effects
- Receptor Agonists vs Antagonists: A Plain-Language Primer
- How Peptides Are Absorbed: The Bioavailability Problem
- Oral vs Injectable Peptides: Why the Route Matters
- Peptide Half-Life, Explained: Why Dosing Frequency Varies
- Do Peptides Actually Work?
Judging the evidence and staying safe
The skeptic’s toolkit: how to read the studies, weigh the risks, and understand the legal and quality picture.
- How to Read a Peptide Study Without Getting Fooled
- Animal Data vs Human Data: The Peptide Translation Gap
- What Phase a Peptide Is In, and Why It Matters
- The Placebo Problem in Peptide Research
- Why Most Peptide Claims Outrun the Evidence
- Why Peptide Dosing in Studies Rarely Matches Marketing
- Peptide Side Effects: What the Safety Data Actually Shows
- Peptides and Cancer Risk: Untangling a Complicated Question
- Peptide Stacking: Why Combining Compounds Multiplies Unknowns
- Peptide Tolerance and Desensitization, Explained
- Peptide Cycling: What the Protocols Claim vs What Is Known
- The Real Risks of Sourcing Peptides Online
- Research Peptides and Purity: What ‘For Research Use Only’ Means
- Are Peptides Legal? The Regulatory Landscape in 2026
- Compounded Peptides and the FDA’s Shifting Stance
- The Economics of Peptide Research: Why Trials Lag
- Reconstitution and Storage: The Science of Peptide Stability
- Acetic Acid as a Peptide Solvent: When and Why It’s Used
- Bacteriostatic Water vs Sterile Water vs Acetic Acid: Choosing a Peptide Diluent
- How to Read a Peptide Certificate of Analysis (COA)
- Injection Technique and Peptides: What the Research Suggests
- Peptides for Women: What the Sex-Specific Data Shows
Growth-hormone peptides & secretagogues
Compounds that aim to raise growth hormone or IGF-1 indirectly: the busiest and most-hyped corner of the field.
- CJC-1295 and Ipamorelin: How the Combo Is Supposed to Work
- CJC-1295 With vs Without DAC: What the Difference Actually Is
- Ipamorelin: A Closer Look at the Growth-Hormone Secretagogue
- Sermorelin: What the Research Shows on the GHRH Analog
- Sermorelin vs CJC-1295: Comparing Two GH Secretagogues
- GHRP-6 vs GHRP-2: Comparing the Older Secretagogues
- Hexarelin: The Forgotten Growth-Hormone Peptide
- MK-677 (Ibutamoren): The Oral Secretagogue, Explained
- Growth Hormone Secretagogues: Do They Beat Direct HGH?
- Tesamorelin: The One Peptide With Real FDA Approval
- GLP-1 vs Growth-Hormone Peptides: Different Goals, Different Evidence
For deeper reading, see Growth-Hormone Peptides: A Complete Guide.
Healing, repair & recovery
The “regeneration” peptides, heavily marketed for injuries and gut health, almost entirely on preclinical evidence.
- BPC-157: Separating the Evidence from the Hype
- BPC-157 and Gut Health: A Closer Look at the Claims
- BPC-157 for Tendons: What the Animal Studies Found
- BPC-157 vs TB-500: For Injury Recovery
- BPC-157 and TB-500 Stack: What the Combo Rationale Is (and Isn’t)
- TB-500: What the Research Does and Doesn’t Show
- Thymosin Beta-4 and Tissue Repair: Reading the Preclinical Data
- KPV: What the Evidence Says About the Anti-Inflammatory Peptide
- Collagen Peptides: One of the Few With Decent Human Data
- Creatine vs Peptides for Recovery: Where the Evidence Stands
- L-Carnitine for Fat Metabolism and Recovery: What the Research Shows
Muscle, fat loss & body composition
Peptides pitched for building muscle or stripping fat, including several cautionary tales.
- Follistatin and Muscle Growth: What the Science Says
- IGF-1 LR3 and PEG-MGF: The Muscle-Building Peptides and Their Risks
- AOD-9604: The Fat-Loss Peptide That Didn’t Pan Out
- Adipotide: A Cautionary Tale in Peptide Development
- Tesofensine: Appetite, Weight, and the Open Questions
- 5-Amino-1MQ: NNMT Inhibition and the Hype Cycle
- SLU-PP-332: The “Exercise Mimetic” Explained
Longevity & mitochondrial peptides
The peptides that show up in anti-aging conversations, from mitochondrial-derived peptides to the bioregulator claims.
- Epitalon: Sorting the Longevity Claims From the Evidence
- Bioregulator Peptides and Aging: A Skeptical Review
- Peptide Bioregulators: Evidence or Marketing?
- Humanin: A Mitochondrial-Derived Peptide Worth Watching
- MOTS-c: The Mitochondrial Peptide, Explained
- SS-31 (Elamipretide): The Mitochondrial Peptide in Trials
- MitoSS-31 vs SS-31: What You’re Actually Getting
Cognition, mood & sleep
- Semax: Nootropic Peptide or Overstated Hype?
- Selank and Anxiety: A Look at the Limited Human Data
- DSIP (Delta Sleep-Inducing Peptide): Does It Help Sleep?
Skin, tanning & cosmetic peptides
Topical and injected peptides marketed for appearance, where “peptide” appears on a lot of labels.
- GHK-Cu: The Copper Peptide Behind the Skin Claims
- Copper Peptides for Hair Loss: What the Evidence Shows
- Cosmetic Peptides in Skincare: Matrixyl, Argireline, and What Works Topically
- Peptides for Skin: Topical vs Injected Evidence
- Melanotan II: Why the Tanning Peptide Carries Real Risks
- Melanotan I vs Melanotan II: Comparing the Tanning Peptides
Immune, reproductive & other
- Thymosin Alpha-1: What We Know About the Immune Peptide
- LL-37: The Antimicrobial Peptide Behind the Buzz
- Kisspeptin: The Peptide Reshaping Reproductive Research
- PT-141 (Bremelanotide): The Evidence on Libido and Arousal
GLP-class research compounds (product codes, not brand names)
Several vendors sell GLP-1-class compounds under product codes (e.g. “GLP-1S,” “GLP-2T,” “GLP-3R”) rather than established molecule names. These pages explain what each code denotes, ground it in the real drug-class evidence, and are explicit that a vendor code is not a guarantee of contents. Identity and purity require a Certificate of Analysis.
- GLP-1S Explained: What the Product Code Denotes and the Evidence Behind It
- GLP-2T Explained: The Dual-Agonist Product Code and the Evidence
- GLP-3R Explained: The Triple-Agonist Product Code and the Evidence
Where to go next
New peptides get added to the Learn library regularly. Browse the full, always-current peptides category for anything not yet listed here. And before acting on anything in this directory, read Peptide Safety: A Practical Framework. None of this is medical advice; decisions about any of these compounds belong with a qualified clinician.
References
- Therapeutic Peptides: Recent Advances in Discovery, Synthesis, and Clinical Translation. Int J Mol Sci. 2025.
- Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
- BPC-157: A prohibited peptide and an unapproved drug found in health and wellness products. Operation Supplement Safety (OPSS), U.S. Department of Defense.
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