Evidence system
How we grade the evidence
Two independent labels appear on every analysis and profile: an evidence level that describes how strong the human research is for a specific claim, and a regulatory status that describes what the FDA has actually decided. One never implies the other.
Evidence levels
The grade applies to a specific claim, population and outcome — never to a molecule in general. A peptide can be established for one indication and preclinical for another. When we can’t verify a claim from a primary source we grade it unsupported rather than guessing.
- Established evidence
- Supported by regulatory approval or multiple strong human trials for the specific indication.
- Typically: FDA approval for the indication, or ≥2 adequately powered randomized trials with consistent results.
- Promising evidence
- Meaningful human evidence exists, but conclusions remain limited.
- Typically: at least one randomized controlled trial or a consistent body of controlled human studies, with meaningful limitations in size, duration or generalisability.
- Preliminary evidence
- Small, uncontrolled, or early-stage human evidence.
- Typically: small pilot studies, uncontrolled or open-label trials, or case series in humans.
- Preclinical evidence
- Cell or animal research only. No adequate human evidence.
- Typically: rodent, other animal or in-vitro studies. Human relevance unknown.
- Unsupported evidence
- Claims exceed the available evidence.
- Typically: marketing claims with no human data, or claims that contradict the available data.
- Conflicting evidence
- Credible studies reach different conclusions.
- Typically: well-designed studies with opposite or inconsistent findings that cannot yet be reconciled.
Regulatory status
Regulatory status is a fact about a decision by the U.S. Food and Drug Administration, not a judgement about evidence. We source it from FDA labels, approval databases and safety communications, and we mark it as requires verification when we cannot confirm it from those sources.
- FDA-approved for this use
- The FDA has approved this peptide for the indication discussed.
- FDA-approved for a different use
- The FDA has approved this peptide for another indication; the use discussed is off-label.
- Investigational
- Under study in registered clinical trials; not approved for marketing.
- Not FDA-approved
- No FDA approval for any indication.
- Withdrawn or discontinued
- Previously available or in development, later withdrawn or discontinued.
- Status requires verification
- The regulatory status could not be verified from primary sources at review time.
Where each peptide sits today
The matrix plots each profiled peptide by overall evidence level (rows) and U.S. regulatory status (columns) for its most-discussed use. Notice how often the two axes disagree.
| Evidence ↓ / Regulatory → | FDA-approved for this use | Not FDA-approved |
|---|---|---|
| Established | ||
| Promising | ||
| Preliminary | ||
| Preclinical |
Analyses by evidence level
Established evidence
- HPLC Purity and LC-MS Identity Answer Two Different Questions
- Endotoxin and Sterility: The Two Tests a Peptide Certificate Almost Never Includes
- Why Peptides Degrade: The Chemistry Behind Storage and Shelf Life
- Why a 10 mg Peptide Vial Does Not Contain 10 mg of Peptide
- Peptides vs SARMs: What's the Difference, and Which Is Safer?
- Which Peptides Are Banned in Sport? The WADA List Explained
- FDA-Approved vs Proven Effective: Why They Are Not the Same
- Counterfeit and Fake GLP-1 Products: How to Spot Them
- Compounded Semaglutide: What the FDA Actually Says
- Best Peptides for Sexual Health: What's Approved and What's Hype
- Are Peptides Steroids? No - Here's the Actual Difference
- How Long Does Semaglutide Take to Work? The Benefit Timeline
- Peptides for Weight Loss: What Works, by How Much, and for How Long
- GLP-1 Benefits Beyond Weight Loss: Heart, Kidney, Liver, and Sleep
- GLP-1 Peptides: Established Uses Versus Emerging Research
- Peptide Purity, Contamination, and the Limits of a Certificate of Analysis
- Tesamorelin: Approved Use, Off-Label Interest, and Clinical Evidence
- PT-141: Mechanism, Approved Use, Benefits, and Limitations
- FDA-Approved, Off-Label, Investigational, and Unapproved Peptides
- How to Read Peptide Research Without Falling for Marketing
- What Are Peptides? A Research-Based Introduction
Promising evidence
- Retatrutide vs Tirzepatide vs Semaglutide: How the Trial Results Compare
- Best Peptides for Beginners: Where the Evidence Actually Is
- Thymosin Alpha-1: The Immune Peptide With Real Human Trials
- Retatrutide: The Triple-Hormone Weight-Loss Drug Still in Trials
- Kisspeptin: The Reproductive Peptide With Real Human Trials for Low Libido
- Best Peptides for Wound Healing and Recovery
- Best Peptides for Women: What the Evidence Supports
- Best Peptides for Men: What the Evidence Supports
- Best Peptides for Joints and Tendons: What Actually Helps
- Best Peptides for Immune Support: The Honest List
- Collagen Peptide Benefits: What to Expect, and When
- Collagen Peptides: Joint, Skin, and Recovery Evidence
Preliminary evidence
- NAD+: What It Is, and What the Human Evidence Actually Shows
- Ipamorelin Benefits: What the Research Actually Shows
- Sermorelin: Benefits, Uses, and What the Evidence Shows
- Melanotan II: The Injectable Tan With Real Safety Concerns
- Copper Peptides vs Retinoids: Comparing the Skin Evidence
- Cerebrolysin: What the Evidence Shows for Stroke and Dementia
- Best Peptides for Focus and Cognition: Semax, Selank, and the Evidence
- The Best Anti-Aging Peptides? What the Evidence Actually Supports
- Peptides for Skin: The Benefits With Human Trials Behind Them
- CJC-1295 and Ipamorelin: Growth Hormone Research and Unanswered Risks
- GHK-Cu: Skin, Hair, Wound Healing, and Evidence Quality
Preclinical evidence
- BPC-157 Benefits: What People Report vs What Is Proven
- Peptides for Hair Growth: What Has Actually Been Tested
- Peptides for Energy and Sleep: Claims Versus Trials
- MOTS-c: The 'Exercise in a Molecule' Peptide, Honestly Assessed
- Best Peptides for Gut Health: What the Research Shows
- Peptides for Muscle Growth: What the Evidence Supports
- Peptides for Recovery: Which Benefits Are Actually Documented
- BPC-157: Human Evidence, Animal Research, and Open Questions
- TB-500 and Thymosin Beta-4: What the Research Actually Studies