What causes black nails?

Nail black line, the most common reason is nail mother nevus, nail mother pigment increased in the body, more common in melanocyte activity enhancement, melanocyte benign, malignant hyperplasia, systemic diseases, or endocrine deficiency caused by nail black line. When nail black line shows widening, and color, shape and other irregularities, should be alert to malignant lesions. Usually pay attention to personal hygiene, often trim nails. Life should be regular, do not stay up late, ensure adequate sleep, pay attention to more rest.