It is a narcotic and may cause withdrawal symptoms if it is stopped too abruptly. Although Norco withdrawal can be quite unpleasant and uncomfortable, you can be assured that it is not life threatening. Norco withdrawal is possible in people who abuse Norco and in people who take Norco for a legitimate medical use.
Definition of melanin for English Language Learners. : a dark brown or black substance that is a natural part of people's skin, hair, and eyes.
Colored pigments in house paint protect the house's siding from sun damage. Melanin is a colored pigment for people, one of several compounds giving skin its coloration, generally contributing shades of red, brown, or black. Melanin is produced by melanocytes.