Causes and Treatment of Dry Skin

US Pharm. 2012;37(4):9-15.

Dry skin (xerosis) is a minor health condition that seldom has serious underlying causes. Further, lack of treatment is not likely to result in serious harm to the patient. Nevertheless, dry skin is a troublesome problem that is experienced by millions of U.S. citizens, so it is probable that the pharmacist will have many opportunities to offer advice on its causes and treatments.

The Prevalence of Xerosis

Virtually everyone will experience xerosis at some time or other, and most either ignore it or self-treat.¹ Surveys conducted in nursing homes and long-term care residences indicate a prevalence of 30% to 75%.^2,3

Normal Epidermal Turnover

The human epidermis is a multi-layered organ, performing many functions, such as protection
from infection and regulation of temperature. Its outer layer (stratum corneum) is composed of dead skin cells that act as a barrier against dehydration of the living layers that lie beneath.⁴ While the stratum corneum helps stop loss of water that is already present, it also is critical in retaining water that contacts it during normal daily activities (e.g., bathing).³

Stratum corneum cells are initially keratinocytes that are generated in the lowest epidermal layer, known as the stratum basale. They undergo serial change as they migrate upward, flattening to become the corneocytes of the stratum corneum. Corneocytes are surrounded by an intercellular substance or “cornified envelope,” composed of a set of cross-linked proteins (e.g., filaggrin, loricrin) and lipids.³ Eventually, the materials at the junctions of the corneocytes break down completely and the dead corneocytes are shed insensibly into the environment.¹ When this normal upward migration is altered, it can disrupt the skin’s barrier function and increase water loss, leading to dry and flaking skin.

Epidemiology of Xerosis

Dermatologists have identified numerous risk factors for xerosis. Some cannot be altered (e.g., age, racial background), but others (e.g., moisture in the ambient air) can be optimized to reduce the incidence of dry skin.²

Age: The association between aging and xerosis is compelling. Experts believe that several aging-related changes coalesce to worsen skin dryness. For instance, sebaceous glands decrease in size with aging, producing fewer lipids to lubricate the skin. Sweat glands also undergo age-related size reduction, so that less moisture reaches the epidermal surface. Corneocytes increase in number and size, forming the well-known dry flakes that are visible on dry skin. The incidence of age-associated dry skin will undoubtedly rise in coming decades as the average age of the population continues to increase.⁵

Ambient Air: Patients of almost any age can develop abnormal skin dryness in adverse climatic conditions. These conditions are most common during the cold, dry winter months. The ability of air to hold moisture is directly related to the outside temperature. Cold winter air is simply incapable of retaining moisture, while hot summer air is saturated with moisture. Being exposed to dry outside winter air for a sufficient time is a guarantee that the outer skin layer will dehydrate, but staying inside is even worse. Forced-air heating systems inside houses and workplaces artificially heat the air inside the buildings. As the air recirculates, it becomes drier and drier with each passing day. Indoor relative humidity may be as low as 10% or less in the winter. During the summer, air conditioners also dry the air, leading to complaints of xerosis.¹

Bathing Habits: Several bathing habits can contribute to dry skin. Patients may use harsh soaps or cleansers or bathe in excessively hot water, both of which are damaging to the stratum corneum.²

Medical Conditions: Patients with diabetes, Sjögren’s syndrome, zinc deficiency, hypothyroidism, HIV, lymphoma, and end-stage renal disease also experience dry skin.^2,5

Medical Therapy: Medications such as diuretics, cholesterol-lowering supplements, antiandrogens, and cimetidine can induce xerosis.² Chemotherapy can make skin dry and more sensitive.⁵

Sequelae of Dry Skin

Most patients do not experience dry skin to the same degree over the total body surface. Moist areas such as the groin and axillae are usually spared, but the rest of the body surface may be dry.² Dry skin feels tight or stiff with a sensation of burning, stinging, and/or itching, and appears erythematous, flaky, rough, and/or scaly.^1,6 When skin
is red and cracked, the condition known as erythema craquelé is said to be present.² Dry skin is the single most common cause of pruritus in older patients.²

If patients scratch the skin obsessively to relieve pruritus, they can excoriate areas that are easily accessible, such as the torso, lower back, arms, and legs.² Excoriated skin is open to infection, and wounds can become chronic. In patients with diabetes, dry skin on the soles of the feet tends to become more hyperkeratotic, increasing the risk of
fissuring, ulcerations, and possibly amputations.⁵

Nonmedical Interventions

Patients can undertake several simple measures to relieve or prevent xerosis. They should avoid outside activities that expose them to dry air and cold wind.¹ Home thermostats should be set as low as possible. During the summer, air conditioners can be set as high as is comfortable. Patients may find it helpful to bathe only every second or third day. This advice is often not well received, so perhaps patients can instead be instructed to limit bath or shower times to 10 minutes, avoiding hot water at all times in favor of warm water. Pharmacists should advise patients that soap worsens dry skin by removing the body’s natural lubricants, and recommend the use of mild, nonscented moisturizing soaps.² Patients should not add oils directly to the bath, as they increase the risk of falling and subsequent traumatic injury. Following the bath, patients should avoid powders on the skin, as they further dry the stratum corneum.² Moisturizers can be applied to the skin twice daily, with one of the applications being directly after the bath or shower.

Clothing can be treated to reduce dry skin damage. Linen and wool garments that contact the skin cause irritation, as their rough surfaces induce friction.¹ Use of fabric softeners on clothing that touches the skin has been demonstrated to reduce friction and may prevent dryness of the skin.¹

Ingredients for Dry Skin

An ideal dry skin treatment should reduce skin dryness, irritation, and pruritus, as well as enhance the skin’s appearance and protective function by restoring the barrier.⁷ Products for dry skin typically contain multiple ingredients, some of which actively reverse dry skin to accomplish the objectives cited above, in addition to other inactive ingredients that are important to the formulation. Dry skin products are referred to as emollients or moisturizers, the latter containing humectants to hydrate the epidermis.⁸ Emollients are oily, lipid formulas that partially occlude the skin, thereby filling in the spaces between unshed corneocytes.⁹ This smooths and softens rough skin, increasing its capacity to retain moisture and reducing inflammation and irritation.⁷ Emollient application can also create a lipid barrier that prevents irritants from damaging the skin.⁷

The FDA has evaluated and approved a specific class of protectants as safe and effective for helping shield chapped or cracked skin from the drying effects of wind and cold weather. Ingredients approved for this use include allantoin, cocoa butter, cod liver oil, dimethicone, glycerin, hard fat, lanolin, mineral oil, petrolatum, and white petrolatum.¹⁰

The various ingredients and others not listed as protectants by the FDA provide slightly different and overlapping benefits for dry skin.⁷ Petrolatum, mineral oil, and paraffin are occlusive, placing an oily layer on the skin surface to prevent evaporation of moisture. Glycerin, lactic acid, glycolic acid, and urea are humectants, a group of materials that draw water from the underlying dermis and help it remain in the stratum corneum. Ceramides, glycerol, urea, and lactic acid also act as rehydrating agents, allowing skin to retain water and reducing water loss. Lipids (fats, waxes, oil) act to restore the skin barrier by forming a film over the surface of the skin.

Many products for dry skin are available. Some trade names are more familiar to pharmacists. They include Vaseline Original, which is 100% petrolatum. Another is Aquaphor, containing petrolatum 41%, mineral oil, lanolin, and glycerin (in addition to inactive ingredients). Velvachol contains water, petrolatum, and mineral oil. Cetaphil Moisturizing Cream contains water and petrolatum.

Urea is an active ingredient that, in concentrations of 2% to 40%, increases hydration of the epidermis.⁵ It is incorporated in Aqua Care, with urea 10%, along with water, mineral oil, and petrolatum.

The dosage form can make a difference in the degree of relief it provides. The ideal dosage form is one that will give a sustained effect. Ointments meet this criterion nicely because of their thick, greasy consistency. In fact, some patients find the ideal remedy for dry hands is to apply petrolatum at bedtime and wear soft cloth gloves all night. Ointments tend to remain on the skin during the day when the patient engages in routine hand washing. However, many patients will not use ointments during the day because of the unpleasant feel. Further, ointments can cause irritation when applied to wounded skin. The drawbacks of ointments make nongreasy creams and lotions popular for daytime use.¹¹ However, washing the hands removes them easily. Lotions are more watery than creams and even more easily removed.

Pediatric Products

Pharmacists should take care in recommending dry skin products for infants. Some products advertised for dry skin in babies contain ingredients that are of unknown safety and efficacy, such as beeswax, castor seed oil, and Peruvian balsam oil. Unproven products are risky at any time, but even more so when the patient is an infant. The area beneath the diaper is wet and occluded by the diaper, creating an environment in which medications can be absorbed to a greater degree.

PATIENT INFORMATION

Causes of Dry Skin

Dry skin is a common condition that is usually self-treatable with nonprescription products such as emollients and moisturizers. It may be caused by a variety of environmental, lifestyle, or medical factors.

Low Humidity: Serious medical conditions can cause dry skin, but such causes are not as common as everyday factors. One of the major contributors is dryness of the air outdoors and in the home or workplace. During the summer, hot air can hold a great deal of water, making for high humidity. During the winter months, however, cold air cannot hold as much moisture, so the outside air becomes very dry. When home furnaces heat the air, it dries out even more, so that inside air in the winter has a very low relative humidity. As people live in dry air, the eyes, throat, respiratory tract, and skin all become abnormally dry.

This is easy to remedy. When the air begins to turn cold in late October or November, run a vaporizer or humidifier in each room where the family lives and sleeps. Be sure to drink a good amount of water every day to help with internal hydration.

Bathing Habits: Dry skin can also be caused by bathing habits. Here are some simple steps to take. Keep baths and showers as short as possible, and use warm rather than hot water. Physicians suggest applying soap only to the face, armpits, and genital area. Switch to mild cleansers such as Aveeno, Dove, Cetaphil, or Neutrogena. Dermatologists advise taking baths only every other day. When drying the skin after bathing, do not rub the towel across the skin. Instead, gently pat the skin dry.

Recommended Products

After bathing and drying, while the skin is still damp, use bath oils and emollient products to help retain moisture. The best products are thick ointments with a greasy consistency, such as Vaseline Petroleum Jelly. Alcohol dries the skin, so products containing it are not as good as ointments.

Avoid scratching itchy areas with your fingernails. Instead, cover any area that itches with a cool wet cloth. Nonprescription hydrocortisone ointments or creams can help if there is some mild inflammation of the skin.

When to See a Physician

Pharmacists may advise patients to see a doctor if the skin is itching but no rash is present, or if dryness and itching are so severe that sleeping becomes difficult. Pay special attention to skin that is open or wounded. Any break in the skin can be the entry point for bacteria. The dryness itself can break the skin open, or vigorous scratching can cause open cuts or sores. If the skin is broken, monitor it closely for signs of infection (swelling, redness, heat, pain) and see a physician as soon as possible to get an antibiotic or antibacterial prescription.

Finally, if the simple steps described above to prevent or treat are not helpful, it is best to see a physician to ensure that there is not a more serious underlying medical problem.

Remember, if you have questions, Consult Your Pharmacist.

REFERENCES

1. Fujimura T, Takagi Y, Sugano I, et al. Real-life use of underwear treated with fabric softeners improved skin dryness by decreasing the friction of fabrics against the skin. Int J Cosmetic Sci. 2011;33:566-571.
2. White-Chu EF, Reddy M. Dry skin in the elderly: complexities of a common problem. Clin Dermatol. 2011;29:37-42.
3. Paul C, Maumus-Robert S, Mazereeuw-Hautier J, et al. Prevalence and risk factors for xerosis in the elderly: a cross-sectional epidemiological study in primary care. Dermatology. 2011;223:260-265.
4. Kawamura A, Ooyama K, Kojima K. Dietary supplementation of gamma-linoleic acid improves skin parameters in subjects with dry skin and mild atopic dermatitis. J Oleo Sci. 2011;60:597-607.
5. Borelli C, Bielfeldt S, Borelli S, et al. Cream or foam in pedal skin care: towards the ideal vehicle for urea used against dry skin. Int J Cosmetic Sci. 2011;33:37-43.
6. Levi K, Weber RJ, Do JQ, Dauskardt RH. Drying stress and damage processes in human stratum corneum. Int J Cosmetic Sci. 2010;32:276-293.
7. Green L. Emollient therapy for dry and inflammatory skin conditions. Nurs Stand. 2011;26:39-46.
8. Loden M. Role of topical emollients and moisturizers in the treatment of dry skin barrier disorders. Am J Clin Dermatol. 2003;4:771-788.
9. Levi K, Kwan A, Rhines AS. Emollient molecule effects on the drying stresses in human stratum corneum. Br J Dermatol. 2010;163:695-703.
10. Skin protectant drug products for over-the-counter human use; final monograph. Fed Regist. 2003;68:33362-33381.
11. Wingfield C. Skin care in the older person: a focus on the use of emollients. Br J Community Nurs. 2011;16:470-478.
12. Questions and answers about Sjögren’s syndrome. National Institute of Arthritis and Musculoskeletal Skin Diseases. www.niams.nih.gov/Health_Info/Sjogrens_Syndrome/. Accessed February 28, 2012.

To comment on this article, contact rdavidson@uspharmacist.com.