Hyaluronic acid is a type of glycosaminoglycan, a substance found naturally in the fluid that bathes joints, connective tissue and in the portion of the eye called the vitreous humor. It’s also abundant in the dermis of the skin, the layer that lies just beneath the epidermis. Here, it’s loosely bound to collagen and elastin fibers that give skin its firmness and ability to “bounce back” and hold its shape. Hyaluronic acid in the skin plays a role in cell growth, but its primary function is to attract and hold onto water. In fact, it can bind water up to a thousand times its own volume. With age, hyaluronic acid levels in the skin decline. Its connections with elastin and collagen fibers are also disrupted. This causes skin to lose some of the firmness and fullness it had in youth.
Because hyaluronic acid can bind and hold onto large amounts of water, it gives the dermis added fullness, causing the overlying skin to look firmer and more youthful. That’s the whole basis behind dermal fillers like Restylane. Restylane is hyaluronic acid that’s been chemically modified so it won’t break down as rapidly. Dermatologists and plastic surgeons use injectable hyaluronic acid fillers like Restylane and Juviderm to add volume to areas of the face and to fill in wrinkles. Hyaluronic acid fillers have largely replaced bovine collagen fillers that were used in the past to fill in wrinkles. Not only is it less expensive, it’s easier to store and there’s no need to do skin testing to rule out an allergy to bovine collagen.
To add volume or fill in a line, dermatologists use a small needle to inject hyaluronic acid filler into the dermal layer of the skin in specific areas that need volume. It can also be injected into the lips to give fuller, more defined lips. Side effects of injections with hyaluronic acid-based fillers like Restylane include possible bruising, transient redness and discomfort during the injection process. For some types of dermal injections, a local nerve block may be used to numb the area, although most people tolerate the injections without significant discomfort. The effects of hyaluronic acid fillers lasts for four months or more before its gradually reabsorbed, and the injections have to be repeated.
Hyaluronic acid has a remarkable capacity to hold onto water. This makes it a popular ingredient in anti-aging skin care products. Some cosmetic and personal care products that may contain hyaluronic acid include facial moisturizers, eye creams, facial cleansers, neck creams, and other products formulated for dry or more mature skin. Hyaluronic acid doesn’t penetrate the outer layer of the skin as readily as sodium hyalurate, the sodium salt of hyaluronic acid, also an ingredient in some moisturizing and anti-aging products.
Sodium hyaluronate, due to its smaller size, is better able to make its way through the epidermis to reach the dermis where it can bind water and mimic the effects of natural hyaluronic acid. Even when hyaluronic acid remains on the surface of the skin, it acts as a powerful humectant, drawing water to the surface of the skin from the environment. Hyaluronic acid is usually combined with an emollient or occlusive moisturizing ingredient to hold in the moisture that hyaluronic acid draws to the skin surface. In very dry environments, hyaluronic acid can be drying since there’s little water to draw from the environment. Therefore, it pulls water from the dermis underneath. Combining it with an occlusive or emollient helps to counteract this to some degree.
Is it safe? These days hyaluronic acid is mostly made by fermenting corn or soybeans instead of harvested from rooster combs as it was in the past. It has an excellent safety profile and is even used to treat joint problems such as osteoarthritis and as a lubricant for dry eyes. The Environmental Working Group’s Skin Deep Cosmetics Database classifies it as a low-hazard ingredient. This also applies to its close cousin, sodium hyaluronate. Hyaluronic acid has few side effects or risks other than possible redness or bruising when used as a filler.