There are black streaks on the neck, there are generally the following reasons: First, long time sun exposure, so that the skin of the neck melanin deposition, there will be black streaks on the neck. Second, acanthosis nigricans, acanthosis nigricans is caused by endocrine disorders, obese people due to the internal endocrine in a state of imbalance, so there will be melanin deposits and rough epidermis on the neck. Third, the use of some drugs can also cause the blackening of the neck, such as contraceptive drugs, corticosteroid drugs, drugs related to thyroid treatment. So if you find black veins on your neck, you should pay attention to find out if there are any of the above reasons, and by avoiding the above reasons, the black veins on your neck will gradually reduce until they fade.