How Does sh-Polypeptide-7 Help Stimulate Hair Follicle Activity or Reduce Scalp Inflammation?

Understanding sh-Polypeptide-7 in Simple Terms

sh-Polypeptide-7 is the cosmetic-industry (INCI) name for a laboratory-made version of human somatotropin — the hormone better known as human growth hormone, or hGH. The "sh-" prefix means synthetic human: the peptide is produced by fermentation, usually in E. coli, from a synthesised copy of the human somatotropin gene. It is worth being precise about this, because sh-Polypeptide-7 is often confused with Epidermal Growth Factor; EGF has its own INCI name, sh-Oligopeptide-1, and is a different molecule with a different receptor.

To understand what a growth-hormone-derived peptide is supposed to do on the scalp, it helps to know what hair follicles are. Hair follicles are tiny structures in the skin that produce hair strands. They cycle through growth (anagen), regression (catagen), and rest (telogen). Inflammation, poor blood supply, or damage to the surrounding skin can interrupt these cycles and contribute to thinning.

Growth hormone works by attaching to a specific receptor on the surface of cells — the growth hormone receptor, or GHR. The receptor acts like a lock and the hormone like a key. When hGH binds the receptor, it triggers internal signalling and, in many tissues, drives production of insulin-like growth factor 1 (IGF-1), which is one of the messengers through which growth hormone acts. Reviews of hair follicle biology report that the growth hormone receptor is present in human hair follicles and that GH and IGF-1 signalling is one of the systems involved in follicle cycling. When that signalling is disturbed — by illness, ageing, or endocrine disease — follicles can shrink, produce thinner hair, or stop producing hair altogether.

That is the biological rationale ingredient suppliers give for putting sh-Polypeptide-7 into scalp products. It is a rationale, not a demonstrated result, and the two should not be confused.

Encouraging Hair Follicle Activity: What Research Suggests

The honest position is that the published research is about the hormone, not about the cosmetic ingredient.

Laboratory work on isolated human hair follicles reports that IGF-1, at concentrations found in the body, helps keep cultured follicles growing and delays their entry into the regression phase. A 2021 review of growth hormone and the human hair follicle collects the evidence that hair follicles carry growth hormone receptors and respond to GH signalling, and it also describes how much remains unresolved.

The criticism of this evidence, applied to a shampoo or serum, is threefold. First, it comes from isolated follicles in culture and from clinical observations in people with growth hormone disorders — not from testing a topical product. Second, growth hormone is a large protein of roughly 191 amino acids; whether a molecule that size crosses the outer layer of the skin in a meaningful amount, and reaches the follicle, is not established for cosmetic formulations. Third, the direction of the effect in endocrine disease is not simple: both growth hormone deficiency and growth hormone excess are associated with hair and skin changes, which is a reminder that more signalling is not automatically better.

There is no published human trial that we could find testing sh-Polypeptide-7 applied to the scalp for hair density or hair count. Claims that the ingredient regrows hair rest on the biology of the hormone and on supplier literature, not on a controlled trial of the product.

Calming the Scalp: sh-Polypeptide-7 and Inflammation Reduction

Inflammation is the body's natural response to irritation or injury, but chronic inflammation on the scalp can harm hair follicles. Conditions such as dandruff, dermatitis, and androgenetic alopecia are associated with increased inflammatory markers, and a calmer scalp is a reasonable goal in its own right.

Growth hormone and IGF-1 are studied in wound healing and tissue repair, and that literature is the usual basis for describing a growth-hormone peptide as skin-repairing. But repair and anti-inflammatory activity are not the same claim, and evidence from wound models or from systemic hormone treatment does not carry over to a leave-on scalp cosmetic.

We could not identify a published clinical study measuring scalp inflammation, redness, or inflammatory markers in people using a sh-Polypeptide-7 product. Where a product is described as soothing, that description generally comes from the brand or the ingredient supplier rather than from an independent trial, and the rest of the formula — humectants, oils, anti-dandruff actives — may be doing the soothing.

The Role of a Healthy Scalp Environment in Hair Growth

Hair follicles do not exist in isolation. They depend on the surrounding skin, blood vessels, and immune cells. When the scalp is inflamed, blood flow can be reduced and irritant substances can build up around follicles.

An ingredient that genuinely supported skin repair and reduced inflammatory signalling could plausibly create a more supportive environment for follicles. That is a plausible mechanism rather than a measured outcome. sh-Polypeptide-7 is not a hair regrowth treatment, and nothing published shows it working as one; at most it is a cosmetic ingredient with a biological story behind it.

Current Limitations and the Need for Human Hair-Specific Studies

The limitations here are substantial and worth stating plainly:

• The mechanism is borrowed from the hormone, and the product is a cosmetic. Cosmetics are not assessed by regulators for hair-growth efficacy.
• Skin penetration of a ~191-amino-acid protein is not established for these formulations.
• There are no published, controlled, human scalp studies of the ingredient for hair density or for inflammation.
• Long-term safety of repeated topical application of a recombinant hormone peptide has not been characterised in published work.
• Growth hormone signalling interacts with IGF-1 pathways throughout the body. Whether topical application produces any systemic exposure is not something the published literature answers.

Growth factors and hormone-derived peptides are best understood as one part of a broader approach that includes proper nutrition, scalp hygiene, and, where appropriate, treatments that have actually been tested for hair loss.

This is a reason for caution rather than optimism. sh-Polypeptide-7 has a coherent mechanism on paper, but it should not be viewed as a treatment for hair loss.

Research Evidence in Detail

The two anchors below are real and verifiable, and neither of them is a study of the cosmetic ingredient:

Philpott and colleagues (1994) cultured isolated human hair follicles and reported that IGF-1, at physiological concentrations, is an important regulator of follicle growth in vitro — supporting IGF-1 as a genuine signal in follicle biology, in a dish, with no product and no scalp.

Horesh, Chéret and Paus (2021) reviewed growth hormone and the human hair follicle, describing GH receptor expression in the follicle and the open questions that remain. A review sets out what is known and unknown; it is not evidence that a topical peptide works.

Four references previously cited on this page — attributed to Choi 2012, Kim 2016, Lee 2011 and Zhang 2018 — were checked against PubMed and did not exist as described; the PMIDs given belonged to entirely unrelated papers. They have been removed rather than repaired, and no numbers from them are repeated here.

sh-Polypeptide-7 is a recombinant form of human growth hormone used as a cosmetic ingredient. Its presence in a scalp product is justified by growth hormone and IGF-1 biology in the hair follicle, not by trials of the product. It may turn out to help; that has not been shown.

Human growth hormone itself is a prescription medicine in most countries, and injectable or systemically dosed growth hormone is not a hair-loss treatment and carries real risks. Talk to a doctor or pharmacist before starting, stopping, or combining any hair-loss treatment, and before using any hormone-derived product — particularly if you are pregnant, breastfeeding, or have diabetes, a history of cancer, or any endocrine condition.

References (APA 7 Format)

Philpott, M. P., Sanders, D. A., & Kealey, T. (1994). Effects of insulin and insulin-like growth factors on cultured human hair follicles: IGF-I at physiologic concentrations is an important regulator of hair follicle growth in vitro. Journal of Investigative Dermatology, 102(6), 857–861. https://pubmed.ncbi.nlm.nih.gov/8006448/

Horesh, E. J., Chéret, J., & Paus, R. (2021). Growth hormone and the human hair follicle. International Journal of Molecular Sciences, 22(24), 13205. https://pubmed.ncbi.nlm.nih.gov/34948002/

COSMILE Europe. sh-Polypeptide-7 — ingredient entry (identifies the INCI name as recombinant human somatotropin). https://cosmileeurope.eu/inci/detail/14380/sh-polypeptide-7/