Facial cleansers are designed to clear away dirt and grime. Many facial cleansers work double duty–moisturizing skin, soothing irritated skin, reducing the signs of aging or repairing damaged facial skin. Not all facial cleansers live up to their claims. It's important to examine the ingredients in facial cleansers to determine whether they serve the purposes advertised by the manufacturer. Despite their many claims, most facial cleansers contain many of the same basic ingredients.

Facial cleansers include detergents and soaps--ingredients that mix with dirt and oils, allowing them to be washed off the skin. The difference between a detergent and a soap largely depends on the ingredients: detergents are synthetic cleansers, and soaps are natural cleansers, as noted in "A Consumer's Dictionary of Cosmetic Ingredients."

"Cosmetics Unmasked" lists sodium lauryl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, ammonium laureth sulfate, stearic acid, lauric acid, myristic acid, oleic acid and palmitic acid as just a few of the common detergents found in facial cleansers.

Soaps may be made from vegetable oil or animal fats. Coconut oil, olive oil, safflower oil, jojoba oil and tallow are ingredients used in creating soap-based facial cleansers. These ingredients are mixed with an alkaline substance, usually sodium hydroxide, or lye, to create a salt. When mixed, in a process called saponification, two byproducts are created--glycerin, a moisturizer, and salt. The salt is what's known as soap.

Moisturizers soothe dry skin and replace oils removed by cleansers. Even some facial cleansers designed for oily skin contain moisturizers to counteract the cleansing agents used in the formula. Moisturizers are occlusive or nonocclusive.

Occlusive moisturizers form a thin, film-like barrier over the skin's surface to prevent moisture loss. Examples of occlusive moisturizers include dimethicone and other silicone-based ingredients, lanolin and petroleum byproducts like mineral oil and petrolatum.

Non-occlusive moisturizers are usually humectants or hygroscopic ingredients–substances that draw moisture to the skin and hold it there for a short period of time while the skin absorbs it. Examples of non-occlusive moisturizers include glycerin, oatmeal, hyaluronic acid and sodium PCA. Oils may also be included in facial cleansers as moisturizing ingredients; olive oil, jojoba oil and some essential oils serve this purpose.

Antimicrobial ingredients can serve two purposes: extending the shelf life of the product and removing potentially harmful or irritating microorganisms from the skin. Antimicrobial chemicals designed to extend the shelf life of facial cleansers include methylparaben, propylparaben, phenoxyethanol, DMDM hydantoin, methylchloroisothiazolinone and methylisothiazolinone. Facial cleansers aimed at those suffering from acne, dry skin or other skin disorders may purposely include antimicrobial ingredients for the purpose of aiding in the treatment of those conditions. Examples of ingredients used in facial cleansers for this purpose include benzoyl peroxide, sulfure, azaleic acid, tea tree oil and honey.