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What are peptides used for?
Skincare, joint and skin supplements, prescription medicine for diabetes and weight management, and a large, loudly marketed grey market of unproven injectable compounds. Same word, four very different levels of evidence.
On this page
In brief
Should you care? Yes — this page is a map, not a verdict on any one use. The point is that “peptides are used for X” is true for several very different values of X, with wildly different amounts of evidence behind each.The short version
- Strong evidence: approved prescription peptide medicines; some cosmetic and collagen uses.
- Moderate evidence: some cosmetic peptides, judged individually.
- Weak evidence, loud marketing: most of the grey-market injectable category.
Four broad uses
| Use | Examples |
|---|---|
| Skincare | Copper peptide, Matrixyl, Argireline — collagen support and muscle-signal dampening |
| Supplements | Collagen peptides, marketed for skin and joint support |
| Prescription medicine | Semaglutide and tirzepatide (diabetes, weight management), insulin, and other approved peptide drugs |
| Investigational / grey-market | BPC-157, TB-500 and similar, sold online despite lacking human trial evidence or regulatory approval |
Where the evidence is genuinely strong
Approved prescription peptide medicines have the deepest evidence base by a wide margin — large randomised controlled trials, regulatory review, and years of post-approval monitoring. Within skincare, a small number of specific peptides (not the category as a whole) have real human trial data, covered individually in the Library.
Where the evidence is thin but the marketing is loud
The grey-market injectable category is where the gap between marketing volume and evidence quality is widest. Compounds like BPC-157 are extensively discussed online and heavily marketed, on evidence that is, as of this page’s review, almost entirely from animal studies rather than controlled human trials. The same pattern shows up even within a single well-studied molecule, where one use (skin collagen) has strong evidence and another (hair growth) borrows the same credibility with none.
How to tell which one you’re looking at
Check the specific compound’s own page rather than trusting the general category. The types hub routes to every category the Library covers, and each individual page states its evidence grade plainly rather than assuming "it’s a peptide" settles the question.
References
- General survey of peptide therapeutic and cosmetic use categories. See individual Library pages for specific evidence.