Normal skin has a soft, supple texture because of its water content. For skin to feel soft, pliable and "normal," its top layer must contain a minimum of 10% water -- and ideally between 20% and 35%. To help protect the outer layer of skin from losing water, the skin's sebaceous glands produce an oily substance called sebum. Sebum is a complex mixture of fatty acids, sugars, waxes and other natural chemicals that form a protective barrier against water evaporation. If the skin doesn't have enough sebum, it loses water and feels dry. If environmental factors cause more water evaporation and overwhelm the ability of sebum to prevent water loss, the skin will shrivel and crack.

Dry skin, also called xerosis, is a very common problem in modern societies, affecting people of all ages, even infants. In the United States, most cases of dry skin are related to one or more of the following factors:

• Decreased production of sebum. This is often a factor in the elderly, since the number and activity of sebaceous glands in the skin tends to decrease with age.
  
  
• Loss of existing sebum. This usually is caused by lifestyle factors, such as excessive bathing or showering, excessive scrubbing of the skin while washing, or harsh soaps that dissolve the protective layer of sebum. In some cases, the result is dry skin over the entire body, especially among school athletes who shower several times a day. In other cases, dry skin affects only the hands; for example, in health care workers, food handlers, house cleaners, homemakers, mothers with children in diapers and others who frequently wash their hands.
  
  
• Environmental conditions that increase water loss. Extreme environmental conditions can overwhelm the skin's natural protective barrier, causing water to evaporate. This is an important reason for dry skin among people who live in sun-baked desert climates, especially in parts of the southwestern United States. Excessively dry indoor air also can cause dry skin and "winter itch" in the northern United States, particularly in people who use forced-air heating systems. Among outdoor athletes, frequent exposure to wind and sun can evaporate water from the skin, making the surface feel itchy and dry. Even swimmers can get dry skin, since the chemical content of pool water actually draws moisture from the skin.
  
  

Dry skin is a common problem in people with diabetes or skin allergies (atopic dermatitis). Less often, it can also be a symptom of hypothyroidism, kidney failure or Sjogren's syndrome. In addition, dry skin sometimes develops as a side effect of medication, especially acne products that are applied to the skin.

Sometimes, the only symptom of dry skin is itching, although most people also will notice that their skin is flaky and slightly more wrinkled than normal. Symptoms of dry skin may worsen during the winter months, especially if you spend a lot of time indoors, where the heated air is dry.

In most cases of uncomplicated dry skin, you can make the diagnosis yourself. Begin by examining your normal skin care routine. Do you often take long, hot baths or showers that may be washing away your skin's protective sebum? Do you shower several times a day or scrub your skin surface with harsh soaps? Do you have a job that requires frequent handwashing?

Next, examine your environmental risk factors, both indoors and outdoors. Do you live in a dry, desert climate? Do you usually spend your winter months indoors, in heated rooms without a humidifier? When you do go outdoors, do you protect your skin with appropriate clothing or with a sunscreen on exposed surfaces? When was the last time you used a moisturizer?

Once you begin to take care of your skin properly, the flakiness and itch of dry skin should improve within one or two weeks. In many cases, a good moisturizer will begin to make your skin look softer and suppler within minutes.

Without proper care, dry skin can become a chronic problem that can lead to skin thickening, cracking and bleeding. This may increase your risk of skin infections.

You can help to prevent dry skin by taking these steps:

• Bathe with comfortably warm (not hot) water, using an unscented soap that either has a high fat content or contains glycerin. Avoid scrubbing.
  
• If you are an athlete, shower off quickly after a workout or game. Use warm water, and bring your own mild soap, since heavy-duty "gym" brands may be too strong.
  
• When you finish your bath or shower, pat dry and immediately apply moisturizer. An unscented moisturizing lotion is easy to apply and will help to maintain skin moisture.
  
• Cover exposed skin when you play outdoors. If you can't wear protective clothing because of hot weather or game regulations, apply a sunscreen with a moisturizer. If you are a swimmer and have problems with dry skin, apply a light layer of petroleum jelly before you enter the pool. Shower when you are out of the pool, pat dry, and immediately apply a moisturizer.
  
• If your indoor air is dry during winter months, use a humidifier to raise the humidity level.
  
• As necessary during the day, apply a moisturizer that contains at least one of the following ingredients: glycerin, urea, pyroglutamic acid, sorbitol, lactic acid, lactate salts or alpha hydroxy acids.
  
• Avoid overusing antiperspirants and perfumes, since these products can dry the skin.

If you have a simple case of dry skin, begin by trying the suggestions outlined in the Prevention section. If your dry skin persists, contact your doctor's office for advice.

Call your primary care doctor or a dermatologist (a doctor who specializes in skin problems) if you have:

• Dry skin that doesn't respond to nonprescription treatments
• Severe itching that interferes with your ability to work or sleep
• Dry skin that cracks and bleeds, or becomes red, swollen and painful

Overall, the prognosis is excellent. You can often prevent dry skin by making a few simple changes in lifestyle. If dry skin develops, there are many soothing and effective treatments available. Most can be purchased without a prescription.

National Institute of Arthritis and Musculoskeletal and Skin Diseases
Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484
Toll-Free: 1-877-226-4267
Fax: 301-718-6366
TTY: 301-565-2966
http://www.niams.nih.gov/

National Institute on Aging
Building 31, Room 5C27
31 Center Drive, MSC 2292
Bethesda, MD 20892
Toll-Free: 1-800-222-2225
http://www.nih.gov/nia/

American Academy of Dermatology
P.O. Box 4014
Schaumburg, IL 60168-4014
Phone: 847-330-0050
Toll-Free: 1-888-462-3376
Fax: 847-330-0050
http://www.aad.org/