Bad skin can be caused by not paying attention to sun protection, irregular life and poor mood. 1. Not paying attention to sun protection: Whether in winter or summer, there are ultraviolet rays in the sun. Long-term exposure of the skin to UV radiation will not only lead to darkening of the skin, but also to aging and wrinkles, thus leading to bad skin. Especially for people with sensitive skin, it is easy to induce solar dermatitis. 2. Irregular life: If patients usually stay up late, it may lead to long-term sleep deprivation, which can easily cause vasoconstriction and slow down the blood flow of the skin, leading to dark skin color, thus causing bad skin. 3. Poor mood: long-term depression or excessive stress may lead to endocrine disorders, lowering immunity and skin condition, thus causing bad skin. It is recommended to keep a good state of mind to help the metabolism of the skin. There are many causes of bad skin, it is recommended that patients go to the dermatology department of a regular hospital, under the guidance of the doctor for examination, diagnosis of the cause of the disease, and follow the doctor’s instructions for treatment.