Due to aging, the outer layer of the skin loses its capacity to retain water inside the skin. Individuals more than 40 years of age show sharp decline in these intracellular lipids, and are more susceptible to dry skin conditions.

Some drugs, such as diuretics, antihistamines and isotretinoin (Accutane) causes skin to dry. 

Alcohol and caffeine can visibly dry your skin
 
During winter months the skin becomes very dry due to low humidity

Deodorant, shampoos and antibacterial soaps dry the scalp. 

Lack of essential lipids, omega-3 fatty acids, zinc and vitamin A in the diet can affect the integrity of the skin. 

Severe diarrhea, vomiting, high fever and sweating can also cause dry skin. 

End-stage renal disease, biliary disorders, diabetes, hyper-parathyroidism and Hodgkin’s disease also cause dry skin disease. 

Many soaps, detergents, and alcohol dry the skin. 

Using hot water during bathing dries the skin. Generally more hotter the water, more are the chances of dry skin. 

Central air and heating wood, burning stoves, space heaters and fireplaces all draw moisture out of your skin.