What Peptides Are Good for Hair? A Look at the Topical Research
Peptides show up in a lot of hair serums now. This covers topical, applied-to-skin research only — not injectable IGF-1, a separate substance and use case — on what has actually been studied and what the studies found.
Search for "peptides for hair" and you will find no shortage of opinions. What is harder to find is a straight account of what the published research actually looked at — which peptides, applied how, and what the studies found. This article covers topical, applied-to-skin research only: IGF-1 and the copper tripeptide family GHK-Cu belongs to. It does not cover injectable IGF-1, which is a different substance, a different use case, and a different regulatory category entirely — not something this article or our topical range has anything to do with.
Topical IGF-1 and the hair growth cycle
Insulin-like Growth Factor 1 (IGF-1) is produced naturally by dermal papilla cells — the signalling centre at the base of each hair follicle. A 2012 study in Clinical and Experimental Dermatology (Castro et al.) tested a topical liposomal IGF-1 gel — applied to the skin, not injected — in a hamster hair-loss model. A 3% IGF-1 gel produced significantly greater hair thickness and growth rate than the control gel and a 1% concentration, with no signs of liver or bone-marrow toxicity and no rise in circulating IGF-1 levels — indicating the topical formulation was not being absorbed systemically. A 2025 review in Current Issues in Molecular Biology (Hsieh et al.) covers the same topical liposomal-gel research alongside the underlying cell biology — IGF-1 activates the PI3K/Akt and MAPK/ERK signalling pathways in follicle cells and increases VEGF expression, supporting blood supply to the follicle — while also noting that topical delivery is limited by the peptide's short half-life and low skin permeability, and that improved delivery formats (like the liposomal gel above) are an active area of research.
Both of these studies are animal research, not human clinical trials, and readers should weigh that accordingly — a hamster model finding is evidence worth reporting, not proof of a human result.
Copper peptides: GHK-Cu and the wider family
GHK-Cu (copper tripeptide-1) is the best-known member of a small family of copper-binding tripeptides. Its most-cited review, by Pickart and Margolina (2018, International Journal of Molecular Sciences), covers its broader regenerative research profile — supporting blood vessel growth, collagen and elastin synthesis, and dermal fibroblast activity — but that review is about tissue repair generally, not hair follicles specifically.
The hair-specific research sits with a related molecule in the same tripeptide-copper family, AHK-Cu. A 2007 study in Archives of Pharmacal Research tested AHK-Cu on human hair follicles ex vivo and on dermal papilla cells in culture, and found it stimulated follicle elongation and papilla cell proliferation, alongside increased VEGF production from dermal fibroblasts. AHK-Cu and GHK-Cu are close relatives — both copper tripeptides — but they are not the same molecule, and it is worth being precise about which one a given study actually tested.
Reading peptide research carefully
Most of the research above is laboratory-based: cultured cells, ex vivo follicle segments, animal models. That is normal for this stage of peptide research, and it is genuinely how promising mechanisms get identified — but it is a different thing from a large, controlled human clinical trial, and readers should treat the two differently. Where a source made a specific numerical claim we could not verify against a real, checkable study, we have left it out rather than repeat it.
What this means for a topical formulation
Our Peptide Hair Growth Serum is formulated with growth-factor peptides from this research area, including sh-Polypeptide-11 (also supplied as CG-aFGF), sh-Oligopeptide-2 (IGF-1), and sh-Polypeptide-9 (VEGF) — the same class of peptides discussed above. This is a cosmetic product for external use, not a medicine, and we make no claim that it replicates clinical trial outcomes; we think the honest, useful thing to do is show you the actual research behind the actual ingredients, so you can judge it yourself.
Sources
Cosmetic product for external application to the skin. Not a medicine; no therapeutic claims are made. Not for ingestion, inhalation or injection. Patch test before first use.