Guide to Skin Creams

When the results of time and sun exposure start to show, many women turn to lotions, creams, and skincare "systems." But do these formulations work?
From Harvard Women's Health Watch

As we get older, our skin undergoes changes that make it feel, act, and look different from younger skin. Its outer cells don't slough off as easily, it doesn't retain as much moisture as it once did, and its support fibers, collagen and elastin, break down. Plus the sun takes its toll. The result is most obvious in our faces, where fine lines appear around the mouth and eyes and the skin sags a bit with the pull of gravity.

The FDA doesn't regulate cosmetic claims, which are allowed without scientific substantiation. Cosmetics can promise to "firm" or "repair" skin or to make you "look younger," and these benefits needn't be proven. But only a few substances have a demonstrated ability to reduce or prevent wrinkles, and even those effects are modest. Fortunately, most skin-care products contain harmless ingredients. Their biggest offense may be their price.

Moisturizers

No moisturizer can make wrinkles disappear or prevent new ones from forming, and none can stop the effects of gravity or photoaging -- the type of aging caused by exposure to sunlight. However, moisturizers can soothe dry skin and temporarily make wrinkles less noticeable.

Petroleum jelly is probably the most effective and least expensive moisturizer, because it coats the skin and seals in moisture. But most women dislike using it on their faces because of its greasy look and feel. Creams (which generally contain more oil than water) and lotions (which are more water-based than creams) are a better choice because of their water content. Many moisturizers are humectants, an oil-free class of moisturizer that reduces the loss of water by binding it to the skin. This helps prolong the product's softening effects.

Most moisturizers contain water, glycerin, petrolatum, stearic acid, and lanolin. Two other common ingredients, propylene glycol and sorbital, both bind moisture to the skin and repel it, canceling out any benefit. Consequently, the American Academy of Dermatology suggests avoiding them. Some skin creams contain botanical ingredients, such as jojoba oil, coconut oil, safflower oil, and linoleic acid, which help maintain the skin's outer protective layer and the natural oils that keep the skin supple. Manufacturers use acetyl alcohol, palmitic acid, and dimethicone to give moisturizers a velvety or translucent look and feel.

Vitamins and Antioxidants

In practice, there's no proof that topically applied vitamins or antioxidants do much at all. Nor is it known whether they remain active long enough to prevent cell damage, promote new collagen production, or confer other benefits.
Vitamin C (ascorbic acid), for example, quickly loses potency when exposed to the air. Thus, it's unlikely that vitamin C in skin creams offers much benefit. Vitamin E (alpha tocopherol) is believed to improve the appearance of scars and help speed wound-healing, but there's no evidence that it does. And in some people, topical vitamin E causes allergic reactions.
Most studies have examined vitamins C and E as potential ingredients in sunscreens rather than as agents meant to reduce or prevent wrinkles. They've demonstrated some effectiveness against UVA and UVB damage. But only vitamins taken internally qualify as antioxidants.

Exfoliants

Aging skin often looks rough and sallow because it doesn't slough off dead surface skin cells as easily as younger skin. Exfoliant ingredients added to moisturizers address this situation, improving the appearance of the skin by removing these cells.

Two chemical exfoliants, alpha hydroxy acids and beta hydroxy acids, lower the skin's pH level; this is believed to renew the skin more effectively than many scrubs, masks, soaps, toners, or abrasive cloths.

Alpha hydroxy acids (AHAs). AHAs are obtained from fruits, including grapes, citrus fruits, and apples. Look for glycolic acid, lactic acid, malic acid, hydroxycaprylic acid, alpha-hydroxyoctanoic acid, triple fruit acid, or sugar-cane extract on the label. AHAs can also cause skin irritation and may increase sensitivity to UV radiation. The FDA has cautioned consumers to use only products that contain an AHA concentration of 10% or less and a pH of 3.5 or more (lower pH numbers are more acidic), and to apply a sunscreen along with AHA-containing products.

AHAs, particularly glycolic acid, are used in chemical peels in concentrations of 20%-30% or higher. An FDA review panel concluded that cosmetologists or skin aestheticians can safely use glycolic acid and lactic acid at concentrations not greater than 30% and with a pH not lower than 3.0 for brief skin-care sessions, provided that thorough rinsing and daily sun protection follow. In higher concentrations, AHAs should be applied only by physicians.

Beta hydroxy acids (BHAs). BHAs are chemically distinct from AHAs and are believed to smooth skin without some of AHAs' irritating effects. The most widely used BHA is salicylic acid, and like its relative aspirin, it has antiinflammatory properties. It also doesn't penetrate as deeply as AHAs do. Moreover, salicylic acid is more effective than AHAs for exfoliating oily areas of the skin, making it useful if you have oily skin or problems with adult acne.

BHAs and salicylic acid can be found in many acne products at effective levels of 1.5%-2%. But anti-wrinkle products containing these ingredients tend not to list the percentage on their labels, so it's difficult to know whether they contain sufficient amounts to be effective. Other BHAs include beta-hydroxybutanoic acid, tropic acid, and trethocanic acid.

The FDA recommends that BHAs first be used on a small patch of skin, to see whether irritation occurs, and that you use a sunscreen with BHA products, as they can increase the skin's sun sensitivity.