The Medical Minute: Dealing with dry skin, a usual winter nuisance

October 09, 2003

By Dr. John Messmer, M.D.
Penn State Milton S. Hershey Medical Center

As the weather turns cooler and we turn on the heat, many of us begin to notice rough, dry skin. As we grow older it becomes more of a problem. Time to head to the store for some moisturizer, but which one is best? Can we do anything to prevent dry skin? If the dryness is associated with cracked skin, redness or is limited to a few areas it might be more than just a seasonal nuisance. It could be a skin disease, such as eczema. But if plain dryness is the problem, the following information may help.

We lose some water through perspiration even in the winter, but this is not a major source of drying for the skin. When we are young, our outer layer of skin is thick and has enough oil to act as a barrier to evaporation through the skin. As we age, the upper layer thins and we do not produce as much oil. This allows water to pass from the skin by evaporation. As the upper layer loses water, the top cells become loose making the skin flaky with a whitish appearance. Many people begin to notice this in their 20's or 30's.

Exposure to dry air makes this worse. A humidifier can slow evaporation and drinking enough fluids helps replenish the skin from inside. Soaps and cleansers have chemicals that remove protective skin oils that normally retain water. Although you might think it should help, letting skin get wet for prolonged periods, such as, washing dishes or soaking in a tub can make it worse. As the wet skin dries, even more water evaporates than was absorbed. Yet, water is what your skin needs to avoid dryness - you just have to trap it in the skin.

There are several ways to trap moisture. Oils are used to form a barrier that keeps water from evaporating, but oils can evaporate also - the lighter the oil, the more quickly it evaporates. Petrolatum or Vaseline is dense mineral oil that does not evaporate easily, but most people do not like the greasy feeling it leaves on the skin. However, if you want a simple and inexpensive way to keep the skin from drying, a very thin coating of petrolatum on sensitive areas after a bath or shower - you must practice to get just the right amount - works very well.

If that does not suit your taste, there are commercial moisturizing creams. Have you looked at a bottle of moisturizer and read the list of ingredients wondering why there are so many chemicals in it? Let's look at the typical moisturizer:

Almost all moisturizers have water as the main ingredient. Various types of oils are mixed with the water - each manufacturer has its own recipe. Oils from plants such as avocado, almond, corn, soybean, jojoba and cocoa and shea butter are examples. Some oils feel better than others on the skin. Lanolin from sheep has been used often, but it can cause an allergic reaction in people sensitive to wool. Since water and oil do not mix, emulsifiers are used to prevent separation otherwise your moisturizer would have to be shaken like salad dressing. Laureth-7, stearic acid and PEG or polyethylene glycol are typical emulsifiers.

Since oils can evaporate leaving the skin unprotected, technology has been developed to deliver oil in tiny spheres called microspheres or nanospheres. These deliver oil deeper into the skin where it is less likely to evaporate. Some products substitute silicones and mono- and di-glycerides for oils to make them oil-free. Oil lets light reflect through skin so the surface becomes more translucent rather than the whitish dry appearance. Some oils can turn rancid after exposure to air so preservatives such as parabens or benzyl alcohol are added.

Some lotions include humectants - chemicals that attract water to increase the amount in the skin. Glycerin, propylene glycol, salicylic acid, lactic acid, urea, hydrolyzed proteins, alpha hydroxyl acids and ammonium lactate are types of commonly used humectants.

Emollients provide a soothing and smoothing action, giving the feeling of softness to the skin. Examples include paraffins, vitamin E, dimethicone and certain other oils. Vitamins such as vitamin E, C and A are added to reduce chemical changes from sun exposure and sun screens such as benzophenone, cinnamates, titanium dioxide and others are often added for sun protection.

Sometimes keratolytics - chemicals that peel the upper layer of skin - are added. Niacinamide and salicylic acid are examples. Retinols are related to vitamin A and help skin repair itself, sometimes reducing fine lines, but they can be irritating. Other ingredients can include thickeners, coloring agents and fragrances.

Because there are so many types of skin, there are many brands of moisturizer. No one product is best for all people. A costly brand is not necessarily better than an inexpensive one but it may feel better or make the skin more translucent and appear healthier or be easier on sensitive skin. But no matter which moisturizer you use, the basic process is add water to the skin and cover it with oil.

(Media Contacts)

Last Updated March 19, 2009