Melanonychia is produced by an excess of melanin causing the nails to take on a blackish color.
A dermatologist is a doctor specialized in diseases of the skin, hair, nails and mucous membranes. Performs diagnoses and treatments for conditions such as acne, psoriasis, dermatitis, skin infections, hair loss and skin cancer. It is advisable to see a dermatologist if symptoms such as persistent rashes, changes in moles, hair loss, brittle nails or any alteration in the skin, hair or nails that do not disappear with basic treatments occur.
Remember that for the proper selection of health professional that treats melanonychia you must consider the nature, severity and symptoms you are presenting.