Thiamine Hcl

Thiamine HCl (vitamin B1 salt) is primarily a skin-conditioning/antioxidant-support ingredient, typically used at low concentrations (about 0.01–1%) and is generally well tolerated in leave-on products. Clinical experience and patch-test literature suggest low irritation overall, but the hydrochloride salt and occasional reports of contact dermatitis mean it is not truly inert, especially on compromised eczematous skin. Given the potential for rare sensitization and stinging on impaired barriers, it fits a "gentle" rather than "very gentle" classification. Safety Notes: In commercial skincare, Thiamine HCl (vitamin B1) is most often a minor supporting vitamin in multi-vitamin/“B-complex” blends, where it can appear at trace levels around 0.0001–0.01% (especially in leave-on serums/creams and some rinse-off cleansers) due to solubility and formula/label-claim positioning. Higher-strength consumer-available products (typically leave-on serums, ampoules, or “vitamin cocktail” concentrates) have been observed using roughly 0.1–0.5%, with occasional high-end/strong niche formulations reaching about 1.0% before practical constraints like odor, saltiness/tack, and pH/compatibility with other actives become limiting. There is no specific EU/FDA maximum for thiamine salts in cosmetics, so the upper end is mainly set by formulation stability/sensory and real-world product practice rather than regulation.