Application de l'acide hyaluronique sur peau humide.

Misconception: Hyaluronic acid only works on damp skin.

During one's skincare routine, it is often recommended to apply hyaluronic acid serum on slightly damp skin to enhance the moisturizing power and effectiveness of the treatment, thereby avoiding the opposite effect of making the skin even drier. But is this really necessary?

Summary
Published January 11, 2023, updated on January 29, 2024, by Stéphanie, Doctorate in Life and Health Sciences — 4 min read

What is hyaluronic acid?

Renowned for its ultra-powerful hydrating properties at low doses, hyaluronic acid is highly favored in the formulation of a wide range of skincare products, ranging from cleansing milk to care cream , through lip treatments and night masks. Its effect? By retaining 1,000 times its weight in water within cells, this active ingredient helps to maintain the skin's natural hydration levels continuously throughout the day, and also protects it from external aggressions that lead to premature aging, loss of radiance, or the appearance of redness.

Already naturally present in the body, hyaluronic acid is an extremely hydrophilic complex sugar composed of D-glucuronic acid and D-N-acetylglucosamine linked together by glycosidic bonds: two sugars that give it the ability to bind water molecules. It notably contributes to the lubrication of joints. In the skin, it fills the spaces between cells, and contributes to hydration and tissue integrity. It also represents one of the essential constituents of the dermis: it is part of the support mattress of the skin along with collagen and elastin.

The hyaluronic acid serum, due to its penetrative power, is among the most popular and effective treatments for improving skin quality on several levels: achieving smoother, brighter skin texture and restoring bounce to the epidermis. However, to take advantage of its properties, certain application tips must be followed.

Should hyaluronic acid be applied on damp skin?

It is often stated that for it to function and be effective, the hyaluronic acid serum must absolutely be applied to damp skin. Applying it to a dry face could have the opposite effect of what is intended and leave the skin more dehydrated. In theory, hyaluronic acid acts like a moisture magnet. Thus, if the skin is dry, it may draw water from the deeper layers of the skin, drying it out. To avoid this phenomenon, one should always ensure that the skin is damp before applying it. As a result, its hydrating powers and effectiveness are amplified by retaining the water provided by the lotion or mist applied beforehand.

In reality, it is not necessary to apply it on damp skin. Firstly, the hyaluronic acid and other humectants do not draw water from the skin like a magnet. They rather "stick" to water molecules through hydrogen bonds and only work over a very short distance. The water must "collide" with the humectant before it binds: it thus acts more like a molecular sponge. Moreover, a serum generally contains up to 80% water, enough for the hyaluronic acid to cling to. Finally, these beliefs have not been scientifically proven.

Thus, regardless of the hyaluronic acid used, they have the same performance, whether applied to wet or dry skin.

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