Peptides are short chains of amino acids that serve as building blocks for proteins, and their use in hair loss and thinning treatments is supported by emerging scientific evidence, though it remains limited and preliminary. In the context of hair health, several types of peptides—such as copper peptides (notably GHK-Cu)—have been studied for their potential to stimulate hair growth and improve scalp health. Laboratory and small-scale clinical studies suggest that certain peptides may promote blood circulation to the scalp, support follicle health, and reduce inflammation, all of which can contribute to healthier hair growth. Copper peptides, for example, have demonstrated the ability to increase the size of hair follicles and prolong the growth (anagen) phase of the hair cycle in some studies.

Despite these promising findings, large-scale, high-quality clinical trials are lacking, and the mechanisms by which peptides may benefit hair growth are not fully understood. Most evidence comes from in vitro experiments, animal studies, or small human trials. While some topical products containing peptides are marketed for hair loss or thinning based on these early findings, the overall quality and quantity of scientific evidence remains modest. Therefore, while the use of peptides for hair support has a scientific basis, it is not yet strongly validated, and further research is needed to establish their efficacy and optimal use.