Rhododendrol, 4-(4-hydroxyphenyl)-2-butanol, Rhododenol(®) (RD), a naturally occurring phenolic compound, was developed as a tyrosinase inhibitor for skin-lightening/whitening cosmetics. In 2013, skin depigmentation was reported in consumers using RD-containing skin-brightening cosmetics; this condition is called RD-induced leukoderma. Rhododendrol exerts melanocyte cytotoxicity via a tyrosinase-dependent mechanism. It has being shown to impair the normal proliferation of melanocytes through reactive oxygen species-dependent activation of GADD45. Rhododendrol (RD) is a potent tyrosinase inhibitor.