Dryness is a medical condition in which there is local or more generalized decrease in normal lubrication of the skin

Human skin

The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...

 or mucous membrane

Mucous membrane

The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

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Examples of local dryness include dry mouth

Xerostomia

Xerostomia is the medical term for the subjective complaint of dry mouth due to a lack of saliva. Xerostomia is sometimes colloquially called pasties, cottonmouth, drooth, or doughmouth. Several diseases, treatments, and medications can cause xerostomia. It can also be exacerbated by smoking or...

, dry eyes, dry skin

Xeroderma

Xeroderma, literally meaning "dry skin", is a condition involving the integumentary system, which in most cases can safely be treated with emollients and/or moisturizers. Xeroderma occurs most commonly on the scalp, lower legs, arms, the knuckles, the sides of the abdomen and thighs...

 and vaginal dryness. These often have specific causes and treatments. It is possible to have dry eyes without any other signs or symptoms, but this usually causes a syndrome of eye symptoms called keratoconjunctivitis sicca

Keratoconjunctivitis sicca

Keratoconjunctivitis sicca , also called keratitis sicca, xerophthalmia or dry eye syndrome is an eye disease caused by eye dryness, which, in turn, is caused by either decreased tear production or increased tear film evaporation. It is found in humans and some animals...

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More generalized dryness can be caused by e.g. dehydration

Dehydration

In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

 (that is, more general loss of body fluids), anticholinergic

Anticholinergic

An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....

 drugs and Sjögren syndrome.