How to Use and Warnings: After cleansing the skin, first tonic and then serum should be applied to your towel-dry skin using cotton. Before using it, apply it to a small area of your skin to prevent possible side effects and irritation - if no sensitivity occurs, you can continue using it. If sensitivity occurs, discontinue use. The Beta Hydroxy Acid it contains may cause sensitivity to the sun on your skin - so you need to apply sunscreen from the moment you start using it. For external use - keep in its original packaging away from direct sunlight.