Hyaluronic acid is a prominent ingredient in skincare, frequently highlighted for its hydrating properties. As a substance that occurs naturally in the body’s connective tissues, it is a popular component for anyone seeking a moisturized and plump skin appearance. Its reputation is built on its primary function of improving skin hydration.
How Hyaluronic Acid Attracts Water
Hyaluronic acid’s effectiveness stems from its function as a humectant, a substance that draws in and holds onto water. Its molecular structure as a glycosaminoglycan, a long chain of sugar molecules, is responsible for this ability. This structure allows a single molecule to hold up to 1,000 times its mass in water through the formation of hydrogen bonds with the molecule’s hydrophilic, or “water-loving,” sections.
The hydrating action of hyaluronic acid is also influenced by its molecular weight. High molecular weight (HMW) hyaluronic acid consists of larger molecules that remain on the surface of the epidermis, forming a film that helps prevent moisture from evaporating.
In contrast, low molecular weight (LMW) hyaluronic acid is made of smaller fragments that can pass through the outer skin layers to deliver hydration deeper within the skin. Studies show that molecules under 500 kilodaltons (kDa) can be absorbed more effectively. Some formulations combine various molecular weights to offer both surface and deep hydration, aiming to provide a more comprehensive moisturizing effect.
Effects on Skin Hydration
When hyaluronic acid draws moisture to the skin, the influx of water results in a plumping effect, which can temporarily diminish the appearance of fine lines and wrinkles. This added volume helps to smooth out the skin’s surface, creating a fuller, more supple look. The skin becomes visibly more hydrated and radiant.
Beyond immediate visual improvements, this process supports the skin’s overall health. Properly hydrated skin feels smoother and more elastic. Hyaluronic acid contributes to this by helping to maintain the skin’s natural moisture barrier, the outermost layer of the skin which regulates water levels and protects against environmental stressors.
By holding water in this outer layer, hyaluronic acid helps prevent transepidermal water loss (TEWL), the process of water evaporating from the skin’s surface. This action helps keep the skin’s barrier functioning properly, which is necessary for maintaining long-term hydration. A well-supported barrier leads to healthier-looking skin that feels consistently moisturized.
Correct Application for Maximum Benefit
To achieve the best results from a hyaluronic acid product, the application method is important. Since it is a humectant that binds to water, it needs moisture to be present to work effectively. It is recommended to apply hyaluronic acid serums to skin that is already damp. A common technique is to cleanse the face and then, while the skin is still moist, press a few drops of the serum into the skin or use a hydrating mist first.
After applying the serum, it is beneficial to follow up with a moisturizer. This final step helps to “seal” in the hydration provided by the hyaluronic acid. Moisturizers, particularly those with occlusive or emollient ingredients, create a physical barrier on the skin that locks in the moisture and prevents it from evaporating.
When Hyaluronic Acid Can Dehydrate Skin
Despite its reputation as a hydrating ingredient, hyaluronic acid can have the opposite effect in specific circumstances. This occurs in environments with very low humidity, where there is little moisture in the air for the molecule to draw from. In such dry conditions, if a product is applied to dry skin, it may begin to pull moisture from the deeper layers of the skin, such as the dermis, up to the surface where it can evaporate.
This potential for dehydration underscores the importance of the correct application method. Applying the product to damp skin provides an external source of water for the hyaluronic acid to bind with. Following up with an occlusive moisturizer is also a protective measure in dry climates, as it creates a barrier that prevents the newly acquired hydration from escaping.