Vitamin C Enrichment: Packed with high concentrations of Vitamin C, this soap helps fade dark spots, even out skin tone, and enhance luminosity. Vitamin C Lemon Whitening Serum Soap is a brightening cleansing bar formulated with vitamin C, natural lemon extracts, and sometimes collagen or glutathione. It targets dark spots, acne scars, and uneven skin tone to promote a radiant complexion.