Skin Care and Diseases

A Guide to Skin Care Products

Over the counter skin care products, such as lotions, creams, and color cosmetics, generally do one or more of the following:

Condition by moisturizing;
Protect from moisture loss and irritation
Cleanse soils and makeup;
Minimize irritation;
Improve appearance;
Improve the comfort and feel of the skin.

Skin care products usually contain a large number of ingredients:

For general care of the skin, there are moisturizers, sunscreens (ultra violet light absorbers), conditioners, and cleansers (known as surfactants).
For a pleasing smell and a nice feel on the skin, there are fragrances and colorants.
In order to increase the product's shelf life, skin care products contain thickening agents, viscosity control agents (texturizers) and preservatives.

Ingredient Function

Knowledge of the effects of specific ingredients on the skin is very useful in evaluating skin care products.

Moisturizing Agents - Skin moisturizers are designed to improve or maintain skin condition by providing water (hydration) in the upper layers of the stratum corneum. Skin with the proper level of hydration is pliable, supple, and without scales/flaking. Skin can be moisturized with a variety of ingredient types. Often, several moisturizers are present in the same formulation:

A humectant is a hydrating agent - it attracts and binds water to the upper layers of the skin. Glycerin is a humectant commonly found in creams and lotions. In dry skin, the exfoliation process is not normal and the outer layer of the stratum corneum does not shed properly, resulting in the build up of cells and cell products that are observed as skin flakes. Through the process of holding water in the skin, glycerin is believed to facilitate the process of desquamation of the outer layer of stratum corneum and reduces scaling.
An occlusive ingredient retards the evaporation of water from the skin surface, thereby increasing the water content in the upper layers.
A skin protectant protects injured or exposed skin from harmful or annoying stimuli. Examples of such "annoying" stimuli include certain types of cleansing agents, powders, and certain types of cosmetics. These materials can damage the skin by disrupting the lipid bilayers in the upper stratum corneum and/or by penetrating through it to cause an inflammatory response in the epdermis.
An emollient maintains a soft, smooth, and pliable appearance. It also remains on the skin surface, reduces flaking, and/or acts as a lubricant.
An exfoliant assists in the removal of dry, scaly patches from the surface. This process creates a smoother surface composed to cells that are more hydrated than the dry scales that were removed.

Cleansing agents (surfactants) remove soils, including sebum, oils, dirt, sweat, cosmetics, etc., from the skin surface. These materials go to the skin surface and interact with the soils to lift them from the skin surface. Surfactants vary considerably in their effects on the skin itself. Certain surfactants are classified as harsh because they disrupt the lipid bilayers in the stratum corneum, presumably increasing the permeability to other materials. Some surfactants penetrate through the stratum corneum and cause an inflammatory response in the epidermis. Others are much less irritating and are better suited to skin cleansing applications.

Skin care product ingredients classified as biological additives come from a biological (plant or animal) source. The biological origin, however, does not automatically insure that they have biological activity in the skin. Ingredients such as emulsion stabilizers, viscosity-decreasing agents, bulking agents, and binders influence the product's physical properties, creating pleasing formulas that last from manufacture to purchase and use by the consumer. Preservatives prevent the contamination by microbial organisms. Fragrance components and colorants provide desirable qualities during product application and use.

Label Information

You can learn a great deal from the label, particularly if you can determine the functions of the ingredients. Federal regulations in the United States require the ingredients to be listed on the label, in the order of the amount in the product. Unfortunately, you cannot learn the absolute amount of the materials from the label. In most cases, the benefit to the skin of moisturizers and protectants depends upon the amount applied to the skin. More is not necessarily better, but certain minimum amounts are needed to produce the expected effects. You can learn about the function or purpose of each ingredient by looking it up in the index below.

Reading Between the Lines

There are a few things to be mindful of when you look at the label for ingredients and product claims:

Notice how often water is listed as the first ingredient. This means that the product is mostly water. Water is an excellent skin conditioning agent - the best, in fact. The task is not only to provide water to the skin, but also to do it in such a way that the skin retains the water. This helps the skin stay smooth and supple. Putting water on the skin surface is easy, but keeping it there requires other strategies.
Even though the ingredient names sound fancy and complex, they may be quite common.
Fragrances have a large number of individual components, none of which are used at high levels. They are usually the ingredients far down on the list.
Some of the ingredients are there just to keep the others together in a pleasant, uniform, and smooth formulation.

For a list of the functions of common ingredients, click here.

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Last Reviewed: May 08, 2000

Marty O. Visscher, PhD
Executive Director and Scientific Investigator
The Skin Sciences Institute
Cincinnati Children’s Hospital Medical Center
University of Cincinnati