Hyaluronic Acid

Hyaluronic acid sits on top of skin and holds onto water, stopping it from evaporating, keeping your skin hydrated and plump. It’s also found deep within your skin, and its levels decrease with age.

Don’t look to hyaluronic acid to completely replace your natural stores though. It’s large molecule size won’t let it penetrate your skin deeply enough, but it will sit on top of your cheeks prettily.

Your skin is gonna drink this up: Don’t be afraid of the “acid” in the name — it doesn’t behave like other acids since its pH also matches the pH of skin. Harsh-free, baby. Topically, it can also help decrease the appearance of fine lines and wrinkles, since dehydrated skin will make them more prominent.

Where to find it: You can find hyaluronic acid in many skin care products, including serums and moisturizers, and it’s safe to use in large amounts. If you do purchase a serum that’s mostly hyaluronic acid, be sure to apply it over moist skin to maximize hydration.

Also known as HA or Hyaluron, this polysaccharide (or sugar) molecule is actually a substance found naturally in our own bodies. Its claim to fame is that it can hold 1000 times its weight in water, making it a superstar for plumping, firmness, hydration and anti-ageing.

Hyaluronic acid is doubtlessly one of the most well-known skincare ingredients—perhaps you've even tested an HA serum or two. But as we all know, just because something is popular doesn't mean it's effective.

As it turns out, there’s a lot about hyaluronic acid we weren’t aware of—like the difference between it and sodium hyaluronate (which is actually a salt rock). Or how that “99% hyaluronic acid” serum you’ve been slathering on really isn’t 99% hyaluronic acid at all, but rather a mixture of hyaluronic acid and water. We know—what?! So is hyaluronic acid worth the hype? Read on to discover if this hydrator is worth adding to your skincare lineup.

What Is Hyaluronic Acid?

First things first—what exactly is hyaluronic acid? For starters, it’s a molecule that is naturally found in your skin as well as the connective tissue in your body. “Hyaluronic acid is a naturally occurring polysaccharide found in the human body,” Benjamin explains. “It acts as a cushioning and lubrication agent for our joints, nerves, hair, skin, and eyes.”

The reason the beauty industry loves it so much lies in its seemingly magical ability to retain moisture. Studies have proven that hyaluronic acid is amazingly good at bonding with water molecules, making it a key factor in retaining skin moisture.1 Lack of moisture is one of the main culprits of aging skin, which is why this ingredient—which attracts moisture to your skin—is a must-have when it comes to repairing your skin’s moisture barrier.

• Retains moisture: Hyaluronic acid helps replenish and hold cell moisture, leading to hydrated, plump skin.
• Reduces the appearance of wrinkles: Since dehydrated skin is one of the main causes of wrinkles, hyaluronic acid replenishes lost moisture and helps reduce the appearance of any fine lines.
• Safe option for filler: Since hyaluronic acid's composition is so closely-related to substances in our bodies, it works well as a filler that doesn't cause major irritation. It can also add volume to areas like the lips and cheeks, which naturally lose volume over time.
• Fast absorbing: Unlike some skincare products, hyaluronic acid quickly absorbs into the skin, meaning you lose less product.
• Non-irritating: For the most part, hyaluronic acid is non-irritating and safe for use with all skin types.
• Short-Term Injectable: When used as a filler, hyaluronic acid lasts for around a year. It dissolves naturally, meaning you don't have to go in to have the filler removed by a doctor.
• Multiple forms of use: Since you can use hyaluronic acid topically, have it injected, or take it as a supplement, there are plenty of options for how and when you use it.

• Available over-the-counter: Unlike some super skincare ingredients, hyaluronic acid products are available in most beauty and drugstores.

Hyaluronic Acid vs. Sodium Hyaluronate

Here’s the interesting part, though: Hyaluronic acid has a counterpart named sodium hyaluronate. “Sodium hyaluronate is the salt form of HA and is a water-soluble salt that holds 1000 times its weight in water,” Benjamin says. “Ingredients are in salt form because they are more stable and less likely to oxidize.”

Both hyaluronic acid and sodium hyaluronate are used in beauty products, and marketers refer to both as “hyaluronic acid”—but there are some key differences. Namely, sodium hyaluronate has a much smaller molecular size, which allows it to penetrate the skin better: “In skincare, there is a formula determining how well products penetrate the skin using the molecular weight,” Benjamin says. “The lower the weight, the more it can penetrate.”

You know serums that claim they’re made with 75% or even 99% hyaluronic acid? Simply put, they’re not. “Sodium hyaluronate doesn’t come in pure form—it comes in solution form,” Benjamin explains. “It comes to be 1% to 2% of the solution, which is primarily composed of water.”

It gets better—Benjamin claims that if the solution has more than 4% sodium hyaluronate, it can actually dry your skin out. She illustrates this with an analogy: If you put too much salt on a sponge, the salt will pull water out of the sponge and dry it out. In the same way, since sodium hyaluronate is a salt rock, too much of it can draw moisture away from the skin, Benjamin claims. She says that 2% is the highest concentration of hyaluronic acid you can put in a solution without any drying effects.

As for those misleading percentages, Benjamin says there’s not really a way for anyone to know exactly how much hyaluronic acid or sodium hyaluronate they’re really getting in a product without taking it to a lab. “If a product were actually made with 90% HA, it would be a salt rock,” she says. “It’s not truly 90% HA—it’s 90% of the total solution, which is primarily water.” She says the industry standard for hyaluronic acid is 1% and sometimes 2% for over-the-counter products. To have a HA concentration higher than that, you usually have to go to a dermatologist's office.

Side Effects of Hyaluronic Acid

Generally, there aren't any known side effects of hyaluronic acid—at least, the topical versions. But as King points out, hyaluronic acid is often used as a filler, and therefore can cause side effects. "There may be swelling," she notes. But, since HA's so closely-related to natural substances already in the body, most reactions are from the injection itself, not HA.

If you choose to ingest hyaluronic acid, it is proven to reduce the appearance of wrinkles and improve the overall plumpness of skin.2 Plus, most people find that the supplement doesn't have side effects.

How to Use and Apply Hyaluronic Acid

For hyaluronic acid to really penetrate the skin’s surface when applied topically, it actually has to be bioengineered to have a much lower molecular weight.3 Benjamin, who recently launched her own HA Hyaluronic Acid Serum ($130), claims that chemists are able to do so while still maintaining the original hydrating benefits.

Shamban adds that in-office treatments can help hyaluronic acid penetrate more deeply into the skin. "When combined with a Hydra Facial or SaltFacial, for example, serum is infused into the skin for a better or more effective penetration of the smaller molecules than application to the top of the epidermis alone," she says.

For those looking to use hyaluronic acid as a filler, it's obviously best to seek out a doctor's opinion first. Much like topical HA, injectable HA also mimics materials already present in our bodies. "Injecting an HA filler in a gel form through a syringe into the various areas of our face, eyes, or other areas is accepted and remains with the body and is used like our other cells as a 'partner' filling, volumizing that area," Douglas says.