Hair fibre concealers, small protein or plant-based fibres that adhere to existing hair through static charge and add visual density, are an underrated cosmetic option for mild to moderate hair thinning. They can transform the appearance of thinning crowns or part lines within seconds and cost £15–30 per 25g bottle that typically lasts 1–3 months with daily use. For patients not yet pursuing medical treatment, or as a cosmetic adjunct alongside it, fibres provide immediate visible improvement.

Two material categories dominate the market. Keratin fibres (Toppik, Caboki, Boldify) are made from cosmetic keratin processed to bind electrostatically to hair shafts. Cotton-based plant fibres (some Caboki formulations, XFusion) offer slightly different texture and adhesion characteristics. Independent comparison testing suggests keratin fibres generally outperform cotton-based products in colour-matching and adherence, but individual preference varies based on hair texture and styling preferences.

Practical considerations: apply to dry hair, set with hairspray for improved durability, and choose colour matched 1–2 shades lighter than your hair to avoid the 'painted scalp' appearance. Limitations are real, fibres won't survive heavy rain, swimming, or significant sweating, and they can transfer to pillowcases. For mild crown thinning or temple hair loss requiring camouflage for specific occasions, the cost-benefit is excellent. For coverage of significant Norwood 4+ loss, fibres become impractical as a daily solution and other approaches (transplantation, SMP, hair systems) become more sensible.