Research-backed concentrations for kojic acid in cosmetic serums range from 0.5% to 2%. Concentrations above 2% can increase the risk of skin sensitization and are not standard in USA retail formulas. Your cosmetic chemist should also consider pH — kojic acid is most stable and effective at a pH between 3.5 and 5.5. AJ Cosmo Labs connects you with chemists experienced in stabilizing kojic acid at effective levels.
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