What causes skin to get darker?

The skin is getting darker and darker, probably due to improper skin care, not paying attention to skin sunscreen and moisturizing, resulting in skin pigmentation, resulting in darker and darker skin. In addition, some chronic skin diseases such as neurodermatitis, eczema, or papular urticaria repeatedly cause pigmentation after inflammation, and long-term use of glucocorticoid ointments can also cause darker and darker skin symptoms. In addition, there are some systemic diseases, such as acanthosis nigricans, which can also cause the skin to become darker and darker. The above health science knowledge is for reference only. The specific situation needs to be checked in a regular hospital and judged by a professional doctor.