Dry skin. Coloured scanning electron micrograph (SEM) of dry skin from the ankle. Lack of vitamin D, vitamin A, niacin, zinc, or iron, can lead to excessively dry skin. Dry skin can have causes that arent due to underlying disease. Examples include dry environment, frequently washing hands, inadequate hydration, swimming in a chlorinated pool or jobs that are rough on the hands such as mechanics or farming. It is also very common in the winter when low humidity leaves skin dry and itchy. Magnification: x650 when printed at 10 centimetres wide.