There may be three reasons: ① Damage to the stratum corneum and decreased water locking ability; ② Only using toner for surface hydration, lacking closed moisturizing ingredients such as ceramides and squalane; ③ Environmental factors (air-conditioned rooms, dry climate) accelerate water loss. It is recommended to use "moisturizing+water locking" products (such as hyaluronic acid essence+moisturizing face cream), and exfoliate regularly to promote absorption.