Whether you’re a Kiehl’s newbie or a skincare-savvy beauty buff, you’ve probably heard of hyaluronic acid. This ultra-popular molecule is one of the most well-known skincare ingredients on the market today, and for good reason. For one, it’s a powerful yet lightweight moisturizer well-tolerated by virtually all skin types. It’s also prevalent in anti-aging products and is celebrated for its ability to absorb quickly and visibly improve the skin’s appearance.

Despite its popularity, there’s a lot you may not know about hyaluronic acid, like how it can also be used in haircare products. Ahead, we’re doing a deep-dive into hyaluronic acid so you can learn all about this miracle ingredient. Read on to discover the most popular hyaluronic acid uses, how it works, and—most importantly—how you can incorporate it in your skincare routine for brighter, younger-looking skin.

What Is Hyaluronic Acid?

Hyaluronic acid is a naturally-occurring substance present in almost all of the body’s tissues. Scientifically, it’s classified as a type of molecule known as a glycosaminoglycan (GAG). Biologically, hyaluronic acid’s primary purpose is to hydrate and lubricate the body’s soft tissue. Approximately half of the body’s natural hyaluronic acid is within the skin; the rest is distributed among other tissues, like the bones and cartilage.I

Hyaluronic acid is a popular and useful ingredient in skincare because of its ability to bind with and retain large amounts of water: Studies show a single hyaluronic acid molecule can hold up to 1,000 times its weight in water.II As such, it’s used extensively in moisturizers and serums, particularly those that target fine lines and wrinkles. Hyaluronic acid is also a common ingredient in some haircare products.

Hyaluronic Acid Benefits For The Skin

There are many valuable benefits of hyaluronic acid as a topical skincare ingredient. Its effectiveness as a moisturizer is probably hyaluronic acid’s best-known use, but it can also help plump the appearance of skin, strengthen the moisture barrier, and promote a more youthful-looking complexion.III Ahead, we’ll teach you everything you need to know about what hyaluronic acid can do for your skin. Plus, discover which Kiehl’s products you can use to reap the complexion-boosting benefits of this holy grail ingredient.

1. It Defends and Strengthens The Skin’s Moisture Barrier

Research indicates that hyaluronic acid is an essential component of the skin barrier. While maintaining moisture and keeping the skin hydrated is its most important function, hyaluronic acid also helps protect the skin from environmental stressors, like pollution and UV exposure. Within the skin barrier, it functions like a “sieve,” allowing some molecules to penetrate the skin’s deeper layers and keeping others out.

We recommend the top-rated Vital Skin-Strengthening Hyaluronic Acid Super Serum to help keep your moisture barrier strong and resilient. This efficacious formula stars a unique form of hyaluronic acid specially engineered to penetrate the skin’s deepest layers. It also contains a blend of adaptogenic botanical extracts, including red ginseng root and holy basil. These powerful ingredients work together to protect the skin from external stressors, like UV exposure, pollution, and harsh temperatures to slow the visible signs of aging. It’s clinically demonstrated to double the skin’s strength and improve resilience* for glowing, healthy-looking skin.**

2. It May Reduce The Appearance Of Fine Lines

As we get older, our body’s natural production of hyaluronic acid and proteins like collagen and elastin decrease, which ultimately leads to fine lines, wrinkles, and other visible signs of aging.IV Hyaluronic acid’s ability to hydrate and plump the appearance of skin instantly makes it a particularly useful weapon in your anti-aging skincare arsenal.

To keep skin looking firm and plump, try incorporating Iris Extract Activating Treatment Essence into your daily skincare routine. This lightweight formula contains hyaluronic acid, iris root extract, and gentle lipo-hydroxy acid. It exfoliates and hydrates the skin for a smoother, more radiant complexion. We recommend using this essence morning and night, after toner but before serum, to prime your skin for more potent anti-aging treatments.

For more intensive treatment of fine lines and wrinkles, try Super Multi-Corrective Anti-Aging Face and Neck Cream. This fast-absorbing moisturizer features hyaluronic acid, phytomimetic vitamin A, and chaga mushroom. The formula works to address key signs of visible aging. After just one month of regular use, you’ll notice smoother skin, less-prominent-looking lines and wrinkles, and a more even complexion.***

3. With The Addition Of Vitamin C, It Boosts Radiance For a Healthy-Looking Glow

In skincare formulations, hyaluronic acid is frequently combined with antioxidant vitamin C. Research indicates hyaluronic acid and vitamin C work in harmony to boost one another’s absorption.IV Studies also show that when used together, these naturally-derived ingredients**** help even the skin tone and improve the appearance of photo-aged, or sun-damaged, skin.V

You can reap these benefits with our top-rated Powerful-Strength Vitamin C Serum, which contains hyaluronic acid and 12.5% vitamin C. It boosts brightness and hydration. This unique water-free serum also visibly diminishes fine lines, reduces the appearance of pores, and helps promote radiance for a healthy-looking glow.

For your eye area, we recommend Powerful-Strength Dark Circle Reducing Vitamin C Serum. This gentle yet effective treatment is clinically demonstrated to reduce the appearance of dark circles, puffiness, and crow’s feet to smooth and refresh tired eyes.***** It’s dermatologist- and ophthalmologist-tested and safe for contact lens wearers. Use your ring finger to lightly dab the treatment around your eye area morning and night for fresher, brighter-looking eyes.

Hyaluronic Acid Benefits For Hair

While there’s extensive evidence to demonstrate the benefits of hyaluronic acid for skin, its usefulness in haircare is less well-studied. That said, some evidence suggests glycosaminoglycans (GAGs) like hyaluronic acid can help thicken the hair shaft and strengthen the hair follicle.VI Research has also shown a correlation between lower levels of GAGs on the scalp and hair loss, brittleness, and dryness. Haircare products with hyaluronic acid may help to improve the appearance of dry hair and help dry strands retain moisture.VII

To help repair weak or brittle hair, lather up with Damage Repairing & Rehydrating Shampoo. This unique formula contains hyaluronic acid, ceramides, and moringa tree oil. The formula helps cleanse and fortify dry, damaged strands. We recommend pairing it with Damage Repairing & Rehydrating Conditioner to help repair and strengthen hair fibers for a lustrous, supple, and manageable mane. This rich conditioner is ideal for ultra-fragile hair or tresses damaged by heat styling or chemical processing.

For an extra boost of softness and hydration, treat strands to Damage Repairing & Rehydrating Leave-In Treatment, which contains hyaluronic acid, ceramides, and coconut oil. Comb the treatment through towel-dried tresses to help hydrate the hair for a smooth, shiny finish. With regular use, this dry hair treatment also helps strengthen hair fibers and replenish damaged strands.