A. Environmental Causes of Itchy Skin
1. Dry Skin
Dry skin (xerosis, winter itch) is common, especially in old people, and may be caused by cold weather, wind, sunburns, prolonged water exposure, frequent hot baths and using soaps (also washing powder and household cleansers) that can thin the protective oil layer on the skin and thus enable losing water through the skin.
2. Sweating
Microbes from a normal skin flora break down the sweat (especially in the armpits and groin) and yield substances that cause itch. Excessive sweatingcan be observed in persons with primary hyperhidrosis (increased activity of sympathetic nerves, possibly caused by psychological reasons), or secondary hyperhidrosis (in elevated levels of thyroxine, in tuberculosis or malignancies).
