Vita-A Rejuvenating Retinol Serum (1% Retinol + Ceramide): You can apply 1-2 drops of Rejuvenating Retinol Serum to your skin in your night routine. Take care to protect your skin with sunscreen during the day. Warnings: For external use only. Before use, apply the product to a small part of your skin to prevent possible undesirable side effects and irritation. If sensitivity does not occur, continue using the product. If sensitivity occurs after application, stop using the product and consult your doctor. Store at room temperature. Do not forget to use sunscreen while using the product. Avoid contact with eyes. In case of contact, wash with plenty of water. It is recommended that pregnant women and those considering pregnancy do not use it. Vitamin B Complex Serum 10% Niacinamide & Vitamin B Complex Serum: Suitable for use in daily routine. Apply 1-2 drops of the product to your face in a thin layer. You can apply it in your day and night routine during periods when your redness and sensitivity complaints increase. Do not forget to use sunscreen while using the product. Brightening & Lightening Vitamin C Serum 10% Ascorbic acid & 0.5% Ferulic Acid: Suitable for use in daily routine. Apply 1-2 drops of the product to your face in a thin layer. We recommend that you use sunscreen daily in your routine where you apply Vitamin C Serum.