Monthly Topic:

“Tis the season of dry skin”

Here’s some helpful information on this common skin ailment.

Xerosis (Dry Skin): Causes and Treatments

Xerosis, or dry skin. In its most severe form, when it takes on the appearance of a rash, it has sometimes been called asteatosis, or xerotic eczema. Dry skin is the most common skin problem for people around the world but it’s severity varies with each individual, their genetics, their hygiene practices and their geographic location.

It’s a common, non-infectious condition most often experienced on the arms, legs and trunk—all areas with relatively few oil glands. With xerosis, the water-binding capacity of the skin is disturbed. The ability of the skin to prevent water loss is probably ensured by different systems in the skin based on natural moisturizing factors, water-retaining substances that consist of a mixture of amino acids and their derivatives, and the epidermal and sebaceous lipids.

Xerosis also describes abnormally dry mucous membranes of the type found in the conjunctiva of the eye or the oral cavity. Generally speaking, the older you are, the more likely you are to suffer from xerosis because the natural thinning of the skin that occurs with age tends to predispose people to dry skin. However, xerosis can occur in children and young and middle-aged adults as well. Even teenagers can have dry, xerotic skin on the non-oily parts of their bodies. Though a distinctly uncomfortable and frequently a long-term problem as well, xerosis can be successfully managed with measures that are both easy to implement and inexpensive.

Causes of xerosis

Xerosis occurs most frequently during the winter months, which in the Northern Hemisphere are times of low humidity. The advent of cold, dry air causes many people to take hot baths and showers, and these two factors work in conjunction to progressively dry out the skin. When the skin dries out, the dead top layer becomes stiff and actually cracks. This cracking phenomenon creates fissures in the skin which then become irritated, inflamed and very itchy. Those with systemic diseases are more likely to develop dry skin. Hypothyroidism, diabetes, kidney disease, atopic dermatitis and psoriasis can also predispose people to xerosis.

The incidence of dry skin increases with aging; almost everyone over 60 years of age is affected. Those with a lifetime history of xerosis are more likely to have it as they get older. According to some estimates, two thirds of all skin diseases in the elderly could be prevented by adequate skin care, including moisturizing regularly. As people age, the number of minute capillary loops – the microscopic blood vessels that provide nourishment, oxygen, immune defense and heat -- that course through the superficial layers of the skin (papillary dermis) decrease. Though this is appropriate for an older person's decreased metabolism, it also impedes fluid exchange, wound healing and heat dissipation. In addition, the connection between the most superficial layer of the skin (the epidermis) to the underlying dermis flattens with age, decreasing the surface area for fluid and nutrient exchange between the dermis and epidermis. Aged epidermis simply has less fluid to be lost. Thus, three chief, age-related skin changes that promote xerosis are decreased vascularity in the superficial dermis, decreased adhesion in epidermal cells and decreased lubrication by the sebaceous glands.

Treatment is simple and effective

Managing xerosis is largely a matter of managing the mechanics of keeping clean, maintaining hydration and minimizing skin trauma. Sufferers should keep the skin lubricated by not taking more than one bath or shower a day and using lukewarm water and mild, non-detergent soap. They should practice the three "gets" of bathing: "Get in, get clean and get out!" Limit soap use to face, armpits, genital area and feet. Interestingly, xerosis is largely a problem of recent years; today people bathe much more frequently than they did in times past, when one or two baths per week was the norm and bodies re-accumulated natural oils between washings. Should you wish to linger in a bath, adding about a teaspoonful of oil to the bath water and soaking for 10 minutes also helps rehydrate the skin. Water should be blotted, not rubbed or toweled vigorously from freshly bathed skin.

Applying a moisturizer to still-damp skin is another beneficial management measure. Alpha hydroxy acids such as lactic acid and glycolic acid, have been shown to increase skin cell turnover. Recent studies have also shown that alpha hydroxy acids can help skin hold onto water, thereby diminishing xerosis. Beta hydroxy acid or salicylic acid preparations have also been shown to increase epidermal cell turnover and to give the skin a smoother appearance. Many people seem to experience less stinging with the beta hydroxy acid preparations than with the alpha hydroxy acid preparations. Both the alpha and beta hydroxy acid preparations are usually applied twice daily in an emollient base.

Ammonium lactate, the commercial form of lactic acid, is available as both a prescription and an over-the-counter or OTC product, useful in treating severe xerosis. Controlled trials show that it restores the normal desquamative (skin-shedding) process, improves the thickness of the viable epidermis and alters the structure of the dermis.

For related information look in our winter newsletter’s feature article on moisturizers:

Moisturizers: An Overview

The information in this article should not be used as a substitute for medical diagnosis, advice or treatment. For specific situations, consult with your doctor or health care professional