Dry skin has a low level of sebum and may be subject to sensitivity. Eczema can cause dry skin. Most dry skin is caused by environmental exposures, such aspsoriasis-This skin condition is characterized by a rapid accumulation of rough, dry, dead skin cells that form thick scales. Thyroid disorders hypothyroidism, a condition that occurs when your thyroid produces too little thyroid hormone, reduces the activity of your sweat and oil glands, which leads to rough, dry skin. Hot baths and showers. Frequent showering or bathing, especially if you like the hot and your baths long, breaks down the lipid barriers in your skin. Dehydration. Severe diarrhea and vomiting, high fever, profuse sweating during exercise, or simply not drinking enough fluids can cause your body to lose more fluid to take in. Weather. In general, the skin is more dry in winter, when temperatures and humidity levels plummet. Winter conditions also tend to make many existing skin conditions worse.