What Does Anhydrous Mean?
Anhydrous is a term that literally means “without water” and is commonly used term in cosmetic & skin care to describe products which contain little or no water.
Advantages of Anhydrous Skin Care Products
Research has shown, as a general rule, anhydrous products have several advantages over high water content products. First, they penetrate the skin barrier more efficiently delivering lipophilic (fat loving/oil soluble) functional ingredients into cells where they are needed. When lipophilic functional ingredients are dissolved in oil based formulations their skin penetration is further enhanced. In contrast, products containing significant amounts of water, and water soluble functional ingredients, do not penetrate the skin barrier as efficiently. This reduces the availability of the active compounds where they are needed at the cellular level (referred to as bioavailability). Second, lipophilic functional compounds tend to be more stable.
A good example is Vitamin C, which in its normal form (ascorbic acid) is water soluble. In this form it does not penetrate into skin very well, and it is very unstable (quickly broken down). By using oil soluble ester forms of Vitamin C (e.g., ascorbyl palmitate, tetrahexydecyl ascorbate) it is more stable, and penetrates in significantly greater amounts. Once within the skin tissue it is converted to regular Vitamin C by an enzyme called an esterase. This same strategy can be used with esters of Vitamin A and Vitamin E.
Other functional ingredients such as antioxidant carotenoids, CoQ10, ferulic acid, alpha lipoic acid, etc. are mostly oil soluble and therefore good choices for topical skin care products. Lastly, products whose primary ingredient is water can actually damage skin if used frequently. The damage results from the drying effects of product water evaporating from the skin surface, and the disruption of skin barrier lipids by emulsifiers (ingredients which allow oil and water to mix).
Water Based Skin Care Products
Clinical tests have shown that many inexpensive cream or lotion “moisturizers” lead to skin damage when used on a regular basis, the exact opposite of what they are intended to do. Ingredients are always listed in order of concentration. Therefore, if water (or aqua) is listed as the first ingredient it is prudent to investigate the product further before purchase.
However, as with most things in life, there are exceptions. For the reasons stated above, avoiding high water content products is generally a better choice for skin care, but some exceptions include certain toners, wrinkle treatments, peels, etc. For these products the functional ingredients are typically water soluble and work best in an aqueous solution, as well these products normally do not contain high concentrations of potentially damaging emulsifiers.