The back of the neck black in daily life is mostly seen in the sun, because ultraviolet radiation can cause melanocytes to secrete too much melanin particles, which leads to skin color deepening, resulting in dark skin, for this situation, should pay attention to good sun protection measures, sunscreen, sunscreen clothing available when going out for protection. In addition, the back of the neck black may also be caused by disease factors, seen in acanthosis nigricans, nigrosis, etc., need to be treated for the cause. 1, acanthosis nigricans: acanthosis nigricans will lead to the neck, armpits, groin and other parts of the dark color looks like black. There are many types of acanthosis nigricans, so you need to go to the hospital to clarify the cause of the disease and the type of disease before symptomatic treatment; 2, acanthosis nigricans: mainly manifested as patches of dark brown patches or blue-gray, with small pigmented spots around the edges of the hair follicles, mostly on the forehead, behind the ears and on both sides of the neck, but also on the forearms, back of the hands, armpits and other places, without conscious symptoms. The lesions progress slowly, from light to dark color for several years, and then quiesce. After diagnosis, patients can take vitamin B and vitamin E internally or inject vitamin C intravenously, and apply hydroquinone cream externally for treatment. In addition, attention should be paid to replacing household items with less frictional and less irritating cotton items, paying attention to wearing light, simple and loose clothing to avoid aggravation of irritation, avoiding contact with suspected allergens and taking measures such as avoiding light, especially in spring and summer when it is advisable to use sunscreen. Usually when the symptoms of back neck darkness are mild, there is no need to worry, pay attention to weight control, regular work and rest, pay attention to sun protection can be, if the symptoms are heavy and external medication still can not be relieved, it is recommended to go to the hospital for examination, under the guidance of the doctor for treatment.