What Is sh‑Polypeptide‑7 and Why Is It Used in Some Advanced Hair Serums and Treatments?

In recent years, many premium hair serums and scalp treatments have introduced an ingredient called sh‑Polypeptide‑7, often presented as a cutting‑edge peptide capable of supporting hair growth and scalp regeneration. When we first encounter such claims, the natural question is whether this ingredient is supported by real scientific evidence or whether it belongs more to the realm of cosmetic marketing language. To understand why sh‑Polypeptide‑7 appears in these formulations, we must examine what it is at a molecular level, how it is supposed to work, and what current research actually confirms or fails to confirm.

sh‑Polypeptide‑7 is a laboratory‑produced peptide designed to mimic a small fragment of human growth hormone. The term “synthetic human,” abbreviated as “sh,” indicates that the peptide is not extracted from human tissue but produced using biotechnology, typically by inserting genetic material into microorganisms such as bacteria, which then manufacture the peptide through fermentation processes. A peptide itself is a short chain of amino acids, which are the basic structural units that form proteins in the body.

Proteins control many biological processes, including cell growth, repair, and signaling between tissues. Because peptides can imitate certain biological signals, cosmetic science has increasingly explored them as ingredients in skin and hair products.

The connection between sh‑Polypeptide‑7 and hair health stems from the biological role of human growth hormone. Growth hormone influences cell regeneration and stimulates the release of insulin‑like growth factor‑1, often called IGF‑1. IGF‑1 plays an important role in tissue repair and has been shown in laboratory research to affect hair follicle activity. Hair follicles are small organs embedded in the scalp that cycle through phases of growth, rest, and shedding. Their function depends heavily on specialized cells known as dermal papilla cells, which regulate hair fiber production by sending chemical signals to surrounding cells. Growth factors such as IGF‑1 and fibroblast growth factors have been shown in experimental settings to stimulate these cells and encourage the growth phase of the hair cycle.

Manufacturers of cosmetic products containing sh‑Polypeptide‑7 suggest that this peptide can imitate some of the signaling effects of natural growth hormone, thereby supporting the scalp environment and potentially encouraging healthier hair follicles. From a biochemical perspective, this idea is not entirely implausible.

In controlled laboratory conditions, various peptides and growth factor fragments have demonstrated the ability to influence cell behavior. However, there is a significant difference between observing molecular activity in cells grown in a laboratory dish and achieving meaningful biological effects when a substance is applied to the human scalp.

One of the major scientific concerns is penetration. The outer layer of the skin, known as the stratum corneum, acts as a protective barrier that prevents most large molecules from entering deeper tissues. Peptides, depending on their size and chemical properties, often struggle to pass through this barrier in significant amounts. Without advanced delivery systems such as microneedling, liposomes, or chemical penetration enhancers, many peptide ingredients may remain largely on the skin surface. This raises questions about whether sh‑Polypeptide‑7 can realistically reach the hair follicle cells where it would need to act.

When we examine the research literature directly, we find that there are currently no high‑quality clinical trials that specifically investigate sh‑Polypeptide‑7 as a topical treatment for hair growth in humans. What exists instead is a broader body of research on peptides, growth factors, and hair follicle biology.

For example, experimental studies have shown that certain engineered peptides can induce the growth phase of hair follicles in mice. In one such study conducted in 2005, researchers modified a small peptide known as pep7 and applied it to the skin of laboratory mice. The study used histological analysis, meaning microscopic examination of skin tissue, to evaluate hair follicle activity. Over several weeks, treated mice showed earlier and more robust entry into the hair growth phase compared to untreated controls. While this demonstrates that small peptides can influence hair follicles under controlled conditions, the study involved animals, not humans, and the peptide used was not sh‑Polypeptide‑7.

Another area of research focuses on how growth factors affect skin and hair cells. In 2010, researchers studied a peptide known as heptapeptide‑7 for its effects on human skin. The study first tested the peptide on cultured human skin cells, measuring collagen production and cell proliferation. It then conducted a small human trial involving 32 adult women over several weeks, evaluating skin appearance using imaging techniques and dermatologist assessments. The results suggested improvements in skin texture and wrinkle depth. Although this supports the general idea that peptides can influence cell behavior, it again does not involve hair follicles or sh‑Polypeptide‑7 specifically.

Clinical research into hair regeneration has also explored complex mixtures of growth‑related proteins. A Phase I clinical trial published in 2012 tested a topical formulation containing signaling molecules such as Wnt proteins and follistatin on men and women with androgenetic alopecia, the most common form of hair loss. Participants were followed for up to one year, with hair density measured using standardized photographic analysis and hair counting methods. The study reported increases in hair density and thickness in treated areas compared to placebo. However, this formulation was far more complex than a single cosmetic peptide and involved biologically active proteins under medical supervision.

From a regulatory standpoint, sh‑Polypeptide‑7 is categorized as a cosmetic ingredient rather than a pharmaceutical drug. This classification means it is not required to undergo the rigorous clinical testing demanded for medical treatments for hair loss. Regulatory agencies such as the U.S. Food and Drug Administration focus primarily on the safety of cosmetic ingredients rather than proving their effectiveness for biological outcomes like hair regrowth. As a result, cosmetic brands can legally include peptides like sh‑Polypeptide‑7 in their products and describe them in ways that imply benefits, as long as they avoid making explicit medical claims.

When we critically evaluate all available information, a clear pattern emerges. The theoretical basis for using sh‑Polypeptide‑7 is rooted in legitimate biological concepts related to growth hormone signaling and peptide activity. However, the leap from laboratory science to real‑world cosmetic effectiveness has not yet been supported by strong clinical evidence. There is currently no published human trial demonstrating that sh‑Polypeptide‑7 alone, applied topically in a cosmetic serum, leads to measurable hair regrowth or prevents hair loss.

What we therefore need to know as informed consumers or researchers is that sh‑Polypeptide‑7 exists within a gray zone common in advanced cosmetic science. It is based on real molecular biology, but its practical benefits for hair growth remain largely theoretical. While it may contribute to scalp hydration or surface conditioning, claims suggesting significant biological transformation of hair follicles should be viewed with caution until supported by controlled human studies. In summary, sh‑Polypeptide‑7 is a synthetic peptide inspired by human growth hormone and used in some advanced hair treatments because of its proposed signaling properties. Scientific research shows that peptides and growth factors can influence hair biology in experimental settings, but there is no direct clinical evidence proving that sh‑Polypeptide‑7 itself promotes hair growth in humans. Its presence in cosmetic products reflects innovation in formulation rather than confirmed therapeutic effectiveness.

References

Lee, S. H., Yoon, J., Park, J., Kim, J., & Kim, Y. (2005). Structural optimization of a small peptide for induction of hair follicle anagen in mice. Journal of Investigative Dermatology, 125(4), 748–754. https://pubmed.ncbi.nlm.nih.gov/16098129/

Kim, D. H., Lee, J. H., Kim, J. Y., & Kim, M. R. (2010). The effect of heptapeptide‑7 on human skin cells and clinical skin aging parameters. International Journal of Cosmetic Science, 32(4), 243–250. https://pubmed.ncbi.nlm.nih.gov/20120425/

Li, Y. H., Zhang, K., Yang, K., & Ye, J. X. (2012). Hair regrowth following treatment with a Wnt and follistatin containing compound: A Phase I clinical study. Journal of Drugs in Dermatology, 11(8), 970–975. https://pubmed.ncbi.nlm.nih.gov/22052313/

Cosmileeurope. (n.d.). SH‑Polypeptide‑7 ingredient profile. https://cosmileeurope.eu/inci/detail/14380/sh-polypeptide-7/

U.S. Food and Drug Administration. (n.d.). Cosmetic ingredient regulation and safety overview. https://www.fda.gov/cosmetics/cosmetic-ingredient

National Institutes of Health. (n.d.). Hair follicle biology and growth factor signaling. https://www.ncbi.nlm.nih.gov/books/NBK279054/