pellagra

pellagra Extreme niacin deficiency, characterized by a rash (dermatitis) on areas of the skin that are exposed to light, trauma and ulcerations within the mouth, diarrhea, mental disorientation (dementia), confusion, delusions, and depression. Pellagra can be fatal if untreated. Proper intake of niacin, a readily available B vitamin, both prevents and cures pellagra. See also niacin.