Most people confuse dehydrated skin with dry skin. Dryness is a skin type and it is caused by the low level of sebum or oil in the skin whereas dehydrated skin is caused by not having enough water in the skin. Dehydrated skin may maintain normal levels of water in the deeper layers of the skin but may not be able to retain it in the outermost layers.
Skin dehydration happens when the outermost layer of the skin starts to evaporate moisture resulting in insufficient internal hydration of the epidermis. Once this damage occurs, the skin will no longer have a good protective barrier and will cause skin problems such as scarring, superficial lines, lack of radiance, loss of elasticity and premature aging.