Rejuvenating serum also suitable for sensitive skin The active ingredient retinol can help increase collagen production in the skin, stimulate epidermal thickness, and inhibit tyrosinase activity. The serum can help reduce wrinkles and fine lines and promote skin firmness, elasticity, and resilience. It can also create a more even complexion and accelerate skin renewal. Note: Use additional sunscreen with SPF 50 during the day.