Skin is Dry Underlying Cause
The skin contains sebaceous glands, which produce oils for the skin surface. The oil helps the skin retain water in the cells, making the skin waterproof. Oil production decreases with age. Conditions that reduce the amount of oil or cause evaporation of water from the skin can cause dryness.
Additional causes of dry skin include:
- Bathing in hot water
- Bathing with strong soap
- Forced air heating
- Sun bathing
- Hair dryer
- Winter season
Continue to Skin is Dry Anatomy
- Hashizume H. Skin aging and dry skin. J Dermatol. 2004 Aug;31(8):603-9. 
- Holden C, English J, Hoare C, Jordan A, Kownacki S, Turnbull R, Staughton RC. Advised best practice for the use of emollients in eczema and other dry skin conditions. J Dermatolog Treat. 2002 Sep;13(3):103-6. 
- Rawlings AV, Matts PJ. Stratum corneum moisturization at the molecular level: an update in relation to the dry skin cycle. J Invest Dermatol. 2005 Jun;124(6):1099-110.