Hair growth is a complex biological process influenced by genetics, hormones, nutrition, and scalp health. Despite the volume of products on the market claiming to stimulate rapid growth, only a limited number of cosmetic ingredients are supported by credible scientific evidence. Understanding how hair growth works at a follicular level is essential to identifying which ingredients can genuinely make a difference.
Hair grows in a continuous cycle consisting of three main phases. The anagen phase is the active growth stage, during which the hair fibre is produced. This phase can last for several years and ultimately determines hair length and density. The catagen phase follows as a brief transition period where growth slows and the follicle begins to shrink. Finally, the telogen phase is the resting stage, during which the hair eventually sheds to allow new growth to begin. Ingredients that support hair growth typically work by prolonging the anagen phase, supporting follicle function, or improving the scalp environment in which follicles operate.
Caffeine: Stimulating Follicle Activity
One of the most widely studied ingredients for hair growth is caffeine. Research suggests that caffeine can stimulate hair follicles by increasing cellular energy and counteracting the effects of dihydrotestosterone (DHT), a hormone linked to certain types of hair loss. When applied topically, caffeine may help support follicle activity, making it a popular choice in leave-on scalp treatments and growth-focused formulations.
Niacinamide: Supporting the Scalp Environment
Niacinamide, also known as vitamin B3, plays an important role in scalp health rather than directly stimulating new hair growth. By improving the skin barrier, increasing microcirculation, and reducing inflammation, niacinamide helps create optimal conditions for healthy hair production. A balanced, well-functioning scalp is critical for long-term hair density, which is why niacinamide is frequently included in modern scalp care and growth-support products.
Peptides: Targeted Follicle Signalling
Peptides have become increasingly prominent in advanced hair growth formulations. Certain biomimetic peptides are designed to communicate with hair follicles, encouraging them to remain in the growth phase for longer periods. While results depend heavily on concentration and delivery, peptides are valued for their targeted mechanisms and their ability to support follicle function when incorporated into well-designed systems.
Rosemary Extract: Botanical Support for Hair Growth
Rosemary extract has gained attention as a botanical ingredient with potential hair growth benefits. Its antioxidant properties and ability to support scalp microcirculation may contribute to improved follicle performance over time. While not a miracle solution, rosemary extract is often used as part of a broader strategy to support scalp health and reduce factors that contribute to thinning or shedding.
Zinc PCA: Maintaining Scalp Balance
Zinc PCA supports hair growth indirectly by helping regulate sebum production and maintain scalp balance. Excess oil, inflammation, and microbial imbalance can negatively affect follicles and contribute to increased shedding. By addressing these underlying scalp issues, zinc PCA helps create an environment more conducive to healthy hair growth.
Why Formulation Matters
Translating hair growth science into a product that performs consistently in the real world requires more than selecting the right ingredients. It demands formulation expertise, testing, and a deep understanding of how actives behave within complete systems. This is where Crafted can help.
Crafted partners with brands to develop hair growth and scalp care formulations grounded in science and built for performance. From selecting clinically supported actives to optimising delivery systems and usage formats, Crafted focuses on ensuring ingredients are used at effective levels and within stable, scalable formulations. This approach helps brands avoid common pitfalls such as under-dosing actives, poor bioavailability, or incompatibilities that reduce efficacy.
Managing expectations is equally important. Hair growth is a slow process, and visible improvements typically require consistent use over several months. Effective products focus not only on stimulating growth but also on reducing excessive shedding, improving the appearance of density, and supporting long-term follicle health.
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Qi, J. and Garza, L.A. (2014) ‘An overview of alopecias’, Cold Spring Harbor Perspectives in Medicine, 4(3), a013615. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3935391/ (Accessed: 3 February 2026).
