Everything you need to know about hyaluronic acid, according to a dermatologist.

In recent years, hyaluronic acid has exploded in popularity as an active ingredient used in many over-the-counter products. After a quick browse at your local drugstore, you’ll find it in serums, face creams and even shampoos. Immediately after application, hyaluronic acid’s moisturizing capabilities get to work to leave skin soft to the touch.

Hyaluronic acid products have garnered cult status in the skincare community, and the hype seems to be justified — studies have backed the use of hyaluronic acid serums to hydrate the skin and smooth fine lines and wrinkles. How do they actually work?

In conversation with USA TODAY, a dermatologist breaks down the science behind using this ingredient to explain why hyaluronic acid should be an absolute staple in your skincare regimen.

How does hyaluronic acid work?

Hyaluronic acid, also known as HA, is an organic substance that already exists inside the human body — mostly occurring in your eyes, skin and joints, says Dr. Rosemarie Ingleton, MD, FAAD, a board-certified dermatologist, medical director of Ingleton Dermatology, and CEO and founder of skincare label ROSE Ingleton MD. When hyaluronic acid binds with cellular water, it swells, resulting in a hydrating effect that locks in moisture and improves skin flexibility, Ingleton explains. 

This process of swelling also gives hyaluronic acid “enhanced space-filling capacity” properties, which is why it’s also frequently used “as a cosmetically elegant dermal filler to fill areas of volume loss,” she says. According to the FDA, facial filler can be used to improve the appearance of skin folds and wrinkles, and when injected into the lips, cheeks and chin, it can add plumpness and structure. 

Why use hyaluronic acid? 

Hyaluronic acid serums and moisturizers are used for rejuvenating dull, dry, winter-time skin that’s in need of extra hydration. According to WebMD, the use of skincare products containing hyaluronic acid is beneficial to rehydrate dry skin and smooth fine lines and wrinkles. However, it’s not only great for your skin — using hyaluronic acid can also help you combat frizz and achieve healthy, glossy hair, per Healthline. When using hyaluronic acid shampoos, conditioners, or leave-in products on your hair and scalp, the ingredient also reduces “dryness and brittleness in the hair shaft and helps to improve the hair’s sheen,” Ingleton adds. 

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How to use products with hyaluronic acid

For most people, hyaluronic acid is easily tolerable on the skin, Ingleton says. Because it’s fairly gentle, hyaluronic acid is one of those ingredients that can be used from day to night. It’s layerable, but you’ll see the best results when you apply hyaluronic acid first onto “clean, slightly damp skin,” she says. After application, Ingleton recommends topping it off with another layer of moisturizer or oil. As for hair products, while it's more common to see hyaluronic acid in shampoos and conditioners, Ingleton says you’ll see the most effective hydrating results on your hair by using hyaluronic acid leave-in conditioners and styling products.