Though most cases of dry skin (xerosis) are caused by environmental exposures, certain diseases also can significantly alter the function and appearance of your skin. Potential causes of dry skin include:
- Weather. In general, your skin is driest in winter, when temperatures and humidity levels plummet. Winter conditions also tend to make many existing skin conditions worse. But the reverse may be true if you live in desert regions, where temperatures can soar, but humidity levels remain low.
- Central heating and air conditioning. Central air and heating, wood-burning stoves, space heaters, and fireplaces all reduce humidity and dry your skin.
- Hot baths and showers. Frequent showering or bathing, especially if you like the water hot and your baths long, breaks down the lipid barriers in your skin. So does frequent swimming, particularly in heavily chlorinated pools.
- Harsh soaps and detergents. Many popular soaps and detergents strip lipids and water from your skin. Deodorant and antibacterial soaps are usually the most damaging, as are many shampoos that dry out your scalp.
- Sun exposure. Like all types of heat, the sun dries your skin. Yet damage from ultraviolet (UV) radiation penetrates far beyond the top layer of skin (epidermis). The most significant damage occurs deep in the dermis, where collagen and elastin fibers break down much more quickly than they should, leading to deep wrinkles and loose, sagging skin. Sun-damaged skin may have the appearance of dry skin.
- Atopic dermatitis. This is one of the more common types of eczema, and those affected have more sensitive and drier skin. Many persons with mild eczema confuse this skin condition with excessive dryness. Areas commonly affected include the face, sides of the neck, and fold areas around the elbows, wrists, knees and ankles.
- Psoriasis. This skin condition is marked by a rapid buildup of rough, dry, dead skin cells that form thick scales.
- Thyroid disorders. Hypothyroidism, a condition that occurs when your thyroid produces too little thyroid hormones, reduces the activity of your sweat and oil glands, leading to rough, dry skin