Dry skin: Common causes, effective treatments

Michael Greenberg, MD, MBA; Heather Galiczynski, ATC, PA-C; Edward M. Galiczynski, Jr.

Dr. Greenberg is Medical Director, Lock Haven University Department of Physician Assistant Studies, Lock Haven, Pa. Ms. Galiczynski practices in Erie, Pa, and Mr. Galiczynski is a student at Lake Erie College of Osteopathic Medicine in Erie. The authors have indicated no relationships to disclose relating to the content of this article.

Ruling out systemic causes is the first step to diagnosing xerosis, and patient education is the key to management. The good news is that dry skin can usually be managed effectively and inexpensively.

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During the winter, dry skin, or xerosis, occurs in more than 75% of persons who live north of the 37th parallel in the United States (roughly the northern half of the country).¹ Dry skin is more common among those who have Fitzpatrick skin type I or II (pale skin), those who work in a low-humidity environment (for example, pilots and flight attendants), health care and restaurant workers who are required to wash their hands frequently, infants, and the elderly.

Although patients rarely present with a chief complaint of dry skin, xerosis is a pervasive disorder that warrants evaluation for an underlying illness. Xerosis itself is a diagnosis of exclusion. Diseases that can cause dry skin and mild generalized pruritus include end-stage renal disease, obstructive hepatobiliary disorders, diabetes, thyroid disease, hyperparathyroidism, and Hodgkin's disease. Dry, pruritic skin rarely signals serious systemic disease, however, and is more typically a symptom of a skin disorder, such as atopic eczema, dyshidrotic dermatitis, ichthyosis vulgaris, stasis dermatitis, psoriasis, and seborrheic dermatitis¹ (see "Common causes of dry skin").

Click here to view full-size graphic

Click here to view full-size graphic

Making the diagnosis of xerosis is straightforward and is based on visual inspection of the skin and patient history. Appropriate management minimizes the likelihood of the emergence or exacerbation of more serious dermatologic problems, such as eczema, cellulitis, furunculosis, psoriasis, seborrheic dermatitis, and dermatoheliosis (sun-induced degenerative changes of the skin).

Anatomy and physiology of dry skin

The skin is the largest organ of the body and provides a formidable barrier both to keep out environmental toxins and to retain water and nutrients.² All three components of the skin—epidermis, dermis, and subcutaneous hypodermis—regulate interstitial water and serve as a protective barrier. The stratum corneum, the outermost layer of the epidermis, consists mainly of dead cells and water and contributes to the skin's elasticity. Although the stratum corneum usually consists of 30% water, the percentage depends largely on ambient humidity.³ Water is a significant component of the inner layers of the stratum corneum.³ The second layer of skin, the dermis, contains elastic and collagen fibers that protect tissue during trauma. Sensory cells in the dermis relay temperature, pain, or itch stimuli information through the nervous system to the brain.⁴ The subcutaneous layer, the deepest layer of skin, contains blood vessels that provide nourishment to the outer layers. All three layers require adequate hydration to protect the underlying structures.⁵ The water content of the stratum corneum has an important role in the skin's elasticity; a water content of less than 10% results in scaling and cracking, which predisposes the underlying skin to irritation.⁶

Onset of xerosis is characterized by dryness and roughness, and skin lines become more defined. As the skin dehydrates, superficial scaling with fissuring and erythema develops. In severe cases, a crisscross pattern appears, along with more pronounced scaling. As the skin loses elasticity, it becomes less resistant to trauma, leading to epidermal breakdown and, possibly, infection.⁷ As the protective barrier breaks down, exposure to environmental factors can lead to more serious skin disorders.

Effective treatment and self-care pearls

Generally, treatment of dry skin centers on retaining moisture and avoiding irritants. This can be accomplished by limiting showers and baths, using only lukewarm or cool water, relying on mild soaps, such as Tone or Dove, wearing only cotton clothing, using only mild, nonperfumed detergents, and avoiding dryer sheets. Patients who have dry skin should understand that although it seems counterintuitive, water has a significant drying effect on skin because it washes off the oils that maintain moisture. Only lukewarm or cooler water should be used when bathing,⁸ because hot water can stimulate histamine release in the skin, which can cause itching, swelling, and dryness.⁹

Soap can adversely affect the natural lubricating and protective elements of the skin. Deodorant, perfumed, and Ivory soaps irritate the skin and remove protective substances and should be avoided. Even mild soaps such as Tone, Dove, and Basis should be used only sparingly on dry skin and as minimally as possible in the axillae, genital area, and feet. When drying wet skin, patients should pat dry rather than rub. Clothes, towels, and sheets should be washed only in nonperfumed soaps and detergents. Use of dryer sheets and fabric softeners should also be avoided.¹

A key component of treatment is the use of both an emollient, which softens and smooths the skin, and a moisturizer, which adds moisture, together immediately after bathing. Effective moisturizers and emollients include OTC products such as urea-based creams and lotions (Carmol, Eucerin), petrolatum (Vaseline Petroleum Jelly), and mineral oil, as well as prescription products that contain ammonium lactate (Lac-Hydrin). OTC products are often effective, however.

Ammonium lactate (lactic acid) is an alpha-hydroxy acid, a normal constituent of tissue and blood. Although alpha-hydroxy acids are humectants that retain water and also attract water to the skin, ammonium lactate works principally as a keratolytic agent. Some patients who may not tolerate the burning and pruritus that are possible with the 12% lactic acid content of Lac-Hydrin may benefit from an OTC urea-based product such as Eucerin. Alternatively, a 6% formulation can be obtained by combining the prescription strength 12% ammonium lactate cream with an equal amount of 1% triamcinolone cream.

Emollients such as urea, mineral oil, and petrolatum provide lubrication and occlusion. Lubricating qualities help replace natural skin lipids, which keep the stratum corneum hydrated.³ An emollient applied to the skin immediately after bathing helps to retain moisture. Emollients applied to the skin are more effective than are gels or oils added to bath water, which can leave the bathtub perilously slippery—an important consideration for the elderly.¹⁰

Dry skin is typically exacerbated during the winter months of low humidity. The term winter itch is used to describe xerotic eczema, which is associated with heated, dry indoor air. Winter itch typically affects the hands and lower legs, which become rough and covered with fine white scales initially. Later, thicker, slightly pigmented scales may appear.¹¹ Increasing the environmental humidity in addition to treating xerotic skin as described above should provide relief.

 

KEY POINTS in this article Dry skin is more common among infants, the elderly, persons who have Fitzpatrick skin type I or II, and those who work in a low-humidity environment or are required to wash their hands frequently. Dry, pruritic skin rarely signals serious systemic disease and is more typically a symptom of a skin disorder, such as atopic eczema, dyshidrotic dermatitis, ichthyosis vulgaris, stasis dermatitis, psoriasis, or seborrheic dermatitis. Retaining the skin's moisture and avoiding irritants are the foundation of patient self-care.

REFERENCES

1. FAA Aeromedical Certification Institute. Aero Medical Surgeons [quarterly newsletter]; Spring 1996.

2. Skin disorders. In: Berkow R, Beers MH, Fletcher AJ, et al, eds. The Merck Manual of Medical Information—Home Edition. New York, NY: McGraw-Hill, 2000:(18)193.

3. Centurion SA. Moisturizers. eMedicine Journal. April 12, 2002;3.

4. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 3rd ed. St Louis, Mo: Mosby; 1996.

5. Aoyama H, Tanaka M, Hara M, et al. Nummular eczema: an addition of senile xerosis unique cutaneous reactivities to environmental aeroallergans. Dermatology. 1999;199(2):135-139.

6. Draelos ZD. Therapeutic moisturizers. Dermatol Clin. 2000;18:597-607.

7. Anderson CA. Asteatotic eczema. eMedicine Journal. November 13, 2001;2.

8. Xerosis (dry skin). The Skin Site. Available at: http://www.skinsite.com/info_xerosis.htm. Accessed July 9, 2004.

9. Lazar AP, Lazar P. Dry skin, water, and lubrication. Dermatol Clin. January 1991;9:45-51.

10. Berger TG. Emollients for dry skin. In: Tierney LM, McPhee SJ, Papadakis MA, eds. Current Medical Diagnosis and Treatment. New York, NY: McGraw-Hill; 2001.

11. Downs M. How's your skin this winter? WebMD Medical News; 2002. Available at: http://webmd.lycos.com/content/article/12/1689_51848. Accessed July 28, 2004.

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