Biotin is present in small amounts in all living cells. It has an important function in the cell metabolism as the coenzyme R when carboxyl groups are transferred, for example during the synthesis of fatty acids. A deficiency of Vitamin H, which is another name for Biotin, may disturb the synthesis of skin lipids. This can cause dermatitis. Other deficiency symptoms comprise hair loss and disturbances of the growth of fingernails. Thus, Biotin is used from within to promote a healthy and beautiful appearance and to prevent deficiency symptoms such as seborrhoea dermatitis. From outside it is frequently formulated in skin care, hair care and nail care products.

Biotin was reported to be effective against hair loss and to improve the hair quality. Furthermore it is formulated in order to harden fingernails and to reduce or prevent their brittleness. So far, most of the underlying literature is referring to oral applications.