There are many causes of skin darkening, which may be influenced by various factors such as hormone level disorders, working environment and personal protection. Hormone disorders within the body can affect skin color, for example, estrogen can stimulate the synthesis of more melanin, while excessive estrogen production during pregnancy or reduced inactivation of estrogen in some people with severe liver disease can lead to darkening of the skin. Skin darkening can also occur when individuals work outdoors in areas with strong ultraviolet rays, or under long-term sunlight exposure such as construction sites, or when they do not pay attention to sunscreen in their daily lives, resulting in hyperfunctioning of melanocytes in the skin. It is recommended to pay attention to the sudden abnormal skin color within a short period of time, and when accompanied by poor mental appetite and other conditions, it is more important to consult a doctor in a timely manner, improve the liver function, endocrine and other auxiliary examinations, and choose the appropriate control or treatment under the guidance of the doctor’s advice.