Just a generation or two ago, our mothers' and grandmothers' moisturizers were created and marketed to moisturize the skin. They worked by retaining skin's moisture. Today's moisturizers are a completely new beast -- addressing more than just retaining moisture. Many are considered to be cosmeceuticals, cosmetics containing natural ingredients that act like pharmaceuticals [source: Perricone].

Some moisturizers add humectants, such as glycerin and alpha hydroxy acids, to help the skin absorb and retain moisture [source: Mayo Clinic Staff]. Some add antioxidants to slow the creation of free radicals that age the skin or retinols (Vitamin A) to slough dead skin [source: MedicineNet.com]. Some add peptides to encourage collagen production or ingredients to lighten and brighten the skin [source: American Academy of Dermatology]. Many add sunscreens, and almost all claim to "reduce the appearance of fine lines and wrinkles." A few even claim to do it all, instantly -- a facelift in a bottle.

With all these choices, how do you select the right moisturizer? Maybe you rely on recommendations from friends and family. Maybe you rely on advertising, trusting the claims on the packaging of a product. Or, you might rely on articles and reviews. If you do rely on advertising or product reviews, you might be wondering how, exactly, they evaluate moisturizers.

Moisturizers were traditionally tested using "open-label" user studies. Test subjects used the product for a short period, with improvement compared to and assessed over the baseline [source: American Academy of Dermatologists]. This standard falls short of scientific double-blind testing, and results are subjective. That changed when Proctor and Gamble conducted a scientifically controlled, longer-term trial on their Olay Pro-x line [source: Geddes]. They proved the claim that their product produced results as good as its prescription counterpart, tretinoin (trans-retinoic-acid). This could encourage other cosmetic companies to upgrade their testing standards.

"Consumer Reports" collaborated with the French to evaluate and rate a number of moisturizers [source: Consumer Reports]. The test ran for 12 weeks and covered an array of product types, from drug-store moisturizers to pricier luxury treatments. Test subjects were women from 30 to 70 years of age with fair skin. In-person and photo evaluations were conducted by dermatologic lab technicians and panels, along with instrument readings.

The Consumer Reports tests showed zero correlation between price and results. In fact, the lowest-priced moisturizer was ranked at the top of the list, surpassing the $335-per-ounce product! The tests also showed no correlation between ingredients and effectiveness, nor did the addition of a sunscreen improve effectiveness. The winner was Olay Regenerist, but each product helped some of the women, each product showed no improvement for some of the women, and the average improvement in "fine lines and wrinkles" was less than 10 percent [source: Consumer Reports].

And if you're wondering where the FDA is in all of this -- the FDA only regulates cosmetics that contain color additives or act as a drug. When a moisturizer is intended to prevent or correct a medical condition, it's also considered a drug. Moisturizers containing sunscreens, for example, are classified as both cosmetics and drugs, and require FDA regulation [source: FDA].

In the end, the true test is in how you evaluate a product. Does it work for you? Are you satisfied with the results? And don't forget that motherly advice, "It's not so much what you use, but that you use it consistently!"

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