by Norman Levine, M.D. Professor and Chief of Dermatology, The University of Arizona College of Medicine
Winter's arrival in Arizona is a welcome relief from the heat, but for many residents it also means the arrival of dry skin. While not a serious health problem, dry skin is an uncomfortable condition that often requires treatment.
In Arizona's desert climate nearly everyone suffers to some extent from skin dryness, but dry skin at this time of year is more common for two reasons. First, lower air temperatures and low humidity result in drier air. This dryness is intensified by forced-air heating in our homes and offices. Dry air increases the evaporation of water from the skin. Second, as we age, we lose the capacity to hold water in the skin. Aging depletes the oil layer that retains moisture in the skin and prevents dry air from drawing water out of our skin. Older adults living in the desert climate have greater difficulty with dry skin during the winter months. Frequent bathing, showering or swimming also remove this protective oil layer.
Contrary to popular belief, the most common symptom of dry skin is itchiness, not flaking. Most people with dry skin are itchy, particularly after bathing. In fact, dry skin is by far the most common cause of itchiness without an obvious rash. Scaliness and dryness aren't synonymous. For example, seborrhea is a skin disease characterized by very scaly areas; however, the skin is oily, not dry -- dead cells on the skin surface form flakes faster than the body can remove them efficiently. If your skin is itchy for no obvious reason, try using a moisturizer before seeing a dermatologist.
Moisturizers, also known as emollients or lubricants, prevent dry air from absorbing water from your skin and help hold water in the skin for a longer time. Although all moisturizers contain water, they do not add this moisture to your skin. Most of the water in moisturizers evaporates shortly after application, leaving behind a layer of protective oil.
Moisturizing products are formulated as either oil-in-water (O/W) or water-in-oil (W/O) emulsions. O/W products are oilier, heavier and stay on better but have a greasy feel that may not appeal to everyone. W/O emulsions are lighter, less greasy and more pleasant to apply, however they rub off more easily than O/W products. Because all water-based products can be contaminated by bacteria, they also contain preservatives.
Oils used in moisturizers may have slightly different properties but all have similar effectiveness in helping the skin retain moisture. Many types of vegetable oils are used; tropical oils, however, are no more effective than others. Animal fats have been used for years because they are inexpensive and easily available; lanolin, for example, closely resembles the oil produced by human sebaceous glands. Mineral oils, derived from petrolatum, such as Vaseline, are effective and inexpensive. Their large molecules stay on the skin surface to provide an excellent barrier. Petroleum-based products used on the face may cause a flare-up of acne in those who are acne-prone. Vitamin E is a fine oil but it doesn't have nutrient value when applied to the skin, and it can cause allergic contact dermatitis (a rash). (Vitamin E taken internally does nothing to relieve dry skin, either.)
Popular but unnecessary moisturizer additives include: collagen and elastin (proteins that are an essential part of normal skin and that hold moisture well, but whose molecules are too large to penetrate the skin); mucopolysaccharides (natural components of the skin that also hold water); miscellaneous protein extracts; vitamin A (a different compound than Retin-A and of no benefit in preventing wrinkles or moisture loss); and liposomes (synthetic pellets, used as carriers for oils, that supposedly penetrate the skin).
When choosing moisturizers, lotions are good for use over the whole body since they are easy to apply and don't stain clothing as much as creams. Creams may be better for localized areas such as the hands, feet and face because they last longer on the skin. Heavy-duty creams or even petrolatum (Vaseline) may be appropriate for exceptionally dry hands or feet. In general, the same moisturizer can be used for the eye area as the rest of the face, just apply it more gently. Bath oils should be avoided because they do not stay on the skin well and make tub surfaces slippery. Fragrance-free products are least likely to cause allergic reactions.
All moisturizers will rub off during the day, so they should be applied at least twice daily. The best times to use moisturizers are after bathing or showering while the skin is still damp and before going to bed, because itchy dry skin will be more bothersome at night when you have no other focus for your senses.
If dry skin persists despite the use of moisturizers, decrease the number of baths or showers you take per week. Avoid long showers or baths, as they dry skin out more. The hardness or softness of the water makes no difference, but tepid water is preferable. Use either a non-drying soap or a water-soluble cleansing lotion (antibacterial cleansers can be drying). If your house has forced-air heat, consider using a humidifier, or leaving exposed pans of water in your rooms to increase the humidity.
If you're still experiencing dry skin after following these recommendations for three weeks, consult a dermatologist; it is possible that your problem is not dry skin but another skin condition that causes itching or scaling.