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Learn the Basics
What peptides are, how research evidence is graded, and how to read what you find online.
What is a peptide?
A peptide is a short chain of amino acids, the same building blocks that make up proteins. The difference is length: proteins are long chains, peptides are short ones. Your body makes thousands of them, and they act as signals — telling cells to release a hormone, repair tissue, or feel full.
Because they are signals, synthetic peptides are studied as medicines. Some have become approved drugs. Most have not.
How to read the evidence
The single most useful question about any peptide is how far through testing it has got. Every page on this site states that plainly near the top.
| Stage | What it means | How much it tells you |
|---|---|---|
| Cell studies | Tested on cells in a dish | Shows a mechanism is possible. Nothing about people. |
| Animal studies | Usually rats or mice | Useful for direction. Most results here never reproduce in humans. |
| Early human trials | Small groups, short periods, safety first | Shows what the body does with it, rarely whether it helps. |
| Large trials | Hundreds or thousands of people, placebo-controlled | This is what approval is based on. |
| Approved | Reviewed by a regulator | Safety, effectiveness and manufacturing quality have been assessed. |
Of the 34 compounds on this site, 8 are FDA-approved medicines. The rest sit somewhere earlier, and several have no published human research at all.
"Research use only" explained
Peptides sold online usually carry a label saying "for research use only" or "not for human consumption." That label is not a safety claim or a quality standard. It describes what the seller says the product is for.
These products are made by unregulated labs. When independent laboratories have tested them, results have frequently not matched the label: in one 2026 analysis of 18 samples of a single compound, only one contained the amount stated.
Questions worth asking
- Has this been tested in people? Not in cells, not in mice — in people.
- Was there a placebo group? Without one, improvement cannot be attributed to the compound.
- Who ran the study, and has anyone else reproduced it? A single research group's results are a starting point, not a conclusion.
- What is actually in the vial? A certificate of analysis on a seller's own website is not independent verification.
Read our guide to concentration math and why it is not a dosing recommendation.