A method of degrading bilirubin in skin is provided. The method involves identifying a target portion of skin where a reduction in bilirubin level is desired, and applying a vitamin B3-containing, low-pH composition to the target portion of skin during a treatment period. The composition contains an effective amount of a vitamin B3 compound, has a pH of less than 5.0, and reduces bilirubin level in the target portion of skin during the treatment period. The amount of vitamin B3 compound and the pH of the composition may be selected to provide a synergistic reduction in bilirubin level, as compared to the reduction in bilirubin level provided by the same composition at a neutral pH.
