My husband has had dark, almost purple
color to his nails, primarily down by the bed of the nail. One doctor said it might be a side effect to one of his blood pressure meds. Another doctor thought it might be due to his hepatitis. Last year, when he was on his second therapy for Hep C, his hepatologist referred him to a dermatologist, who thought he might have cryoglobulinemia, which is a blood disorder that many people with hepatitis have. It was ruled out.