"Kojic acid is a great ingredient derived from mushrooms or fermented rice that can inhibit the formation of tyrosine, an amino acid needed to produce melanin pigment," said Dr. Nussbaum. "Botanical extracts like sophora and emblica have also been clinically shown to prevent melanin transfer from the melanocyte to keratinocytes and therefore greatly enhancing the lightening effects of other ingredients."
The Urban Skin Rx Resurfacing Vitamin C Cleansing Bar ($15) contains kojic acid, as well as niacinamide and lactic acid.