It is used only in the evening. Shake before use. Apply a few drops on cleansed skin by massaging the face, neck and décolleté area. If skin sensitivity occurs, the frequency of use is reduced. Since it contains 6% lactic acid, it may cause sensitivity to the sun, it is recommended to apply sunscreen with at least 30-factor protection every day. If you want to use Aha&Bba products but have sensitive skin, dilute the product.