‘Tis the driest season of the year—and you need a serum. Most of us will already have resorted to slathering on a thicker moisturizer to protect against the elements, but (hate to break it to you) you should really add this step. Cold weather and low humidity put a strain on the skin’s outer layer,” Dr. Joshua Zeichner explains. “This leads to microscopic breaks, loss of hydration, and inflammation. Layer a serum under your moisturizer for an extra layer of protection. Especially in the winter, look for a serum that contains hyaluronic acid which acts like a sponge to pull in water to the outer skin layer to plump and hydrate.”

See, unlike moisturizers, which sit atop the skin, the right serum works to deliver hydration to the skin’s deeper levels—a serum is a “delivery system for a specific ingredient,” Dr. Zeichner says.

And there’s one ingredient featured in ALL of the below product picks. That star ingredient? Hyaluronic acid. Dr. Shreene Idriss explains: “It is a powerful humectant, meaning it attracts water from the deepest layers of your skin up to the most superficial, giving your skin the intense hydration it requires. As an added bonus, it helps plump up those pesky fine lines, leaving you looking smooth and flawless.”

As you’ll see below, however, there are countless forms in which, and sources from which, HA can come. Dr. Dendy Engelman helped break it down.

“Sodium hyaluronate, (an ultra-common form in skincare), is a salt derived from hyaluronic acid. It has all the benefits of hyaluronic acid, but is more easily absorbed than hyaluronic acid, which while advantageous, actually does not make it better than HA,” she says. “Making hyaluronic acid smaller means it can reach a bit farther into skin’s uppermost layers for visibly enhanced results,” she explains. That’s why, ideally (as many of our favorite formulas do), the best serums will combine various molecular weights, or pure hyaluronic acid and sodium hyaluronate—so your skin can reap the benefits on multiple levels.

“Botanically derived products are ideal,” Dr. Engelman explains, referring to some of our choices from our favorite natural brands, “as there are no ethical or purity issues associated with it, but you still get to reap the benefits. Before the introduction of botanically derived HA, animal based sources, like rooster combs, were the main source of HA.” (Eek).

Get ready to hear a LOT more about hyaluronic acid—and discover your perfect, winter-skin-saving formula, right this way.

iS Clinical Hydra-Cool Serum

This serum from derm-approved brand, iS Clinical, harnesses a winning combinations of hydrating, soothing, and yes (!) cooling ingredients. Part of the formula is centella asiatica—this ingredient seems to be popping up everywhere, though this serum (nor the ingredient itself) are new. It’s an ancient herbaceous plant tigers are said to roll around in for its skin-loving benefits. Hydration comes via Vitamin B5, hyaluronic acid, kojic acid, and menthol—which you’ll feel upon application! ($90, Dermstore)

Drunk Elephant B-Hydra Intensive Hydration Gel

Texturally, this serum straddles the line between more watery formulas and ultra-light moisturizers. True to its name, it’s a gel, fortified with Vitamin B5, pineapple ceramide, and a complex containing watermelon rind, apple, and lentil which all help lock in the moisture for longer-lasting results. Barberry extract soothes—and of course, this product has HA too, in the form of Sodium Hyaluronate Crosspolymer, which has a smaller molecular weight than hyaluronic acid, allowing for deeper penetration. ($52, Sephora)

OSEA, Hyaluronic Sea Serum

OSEA’s take on this hero-ingredient combines three molecular weights of Hyaluronic Acid + three organic seaweeds (the company’s hallmark) that work together to draw in moisture from the atmosphere to hydrate, plump and minimize the signs of aging. The seaweed extracts help even skin tone and keep skin firm, and red marine algae extract provides additional moisture. ($88, OSEA Malibu)

Susanne Kaufmann, Hyaluron Serum

This luxe-natural line contains botanically-derived hyaluronic acid in varying weights to achieve multiple layers of hydration. Low molecular weight helps skin’s external structure while high molecular weight helps moisture penetrate skin at a deeper level. ($182, Net-A-Porter)

Peter Thomas Roth, Water Drench Hyaluronic Cloud Serum

This ultra-light serum combines a 75% concentration of hyaluronic acid with a mineral complex that increases the skin’s moisture levels, including bio-fermented copper, zinc, and manganese. Finally, silk proteins leave skin soft and smooth. ($65, Sephora)

Omorovicza, Instant Perfection Serum

All of Omorovicza’s products contain the brand’s signature Hungarian thermal water—this serum included—but that’s just the tip of the iceberg. In the name of, well, instant perfection, this serum uses (of course) hyaluronic acid, which is bolstered by a patented Hydro Mineral Transference™ delivery which system leaves skin firmer, more supple and younger-looking. Narcisuss stem cells help encourage a bright, even complexion, and help repair dark spots, while Rhamnose polysaccharide prevents harmful bacteria from accumulating on the skin's surface, preventing environmental stress caused by pollution and UV. Finally, Xylitol derivatives nourish dehydrated skin by facilitating the intercellular transfer of water (basically, helping moisture move around and get to the cells that need it). ($160, Nordstrom)

Epicuren, Phyt02 Hydration Serum

From one of Kim Kardashian’s favorite beauty companies, comes this hydrating formula that blends, you guessed it, HA, with soothing aloe extract. Amino acids help promote cell turnover and oxygenation of the skin, while Vitamins A, B, C, E, and zinc all help promote healthy cell production. ($95, Epicuren)

NIOD, Multi-Molecular Hyaluronic Complex (MMHC2)

If you’re not familiar—NIOD is like the Apple of skincare—not only are they constantly on the cutting-edge of high-tech ingredients and formulations, but when there are possible improvements to make, they make them—hence the “2” in the highly-scientific name of this formula. That’s because, in this second iteration of the product, there are a whopping fifteen forms of hyaluronic acid. They range in molecular weights and come from sources like mushrooms and locust-beans. There is also a 1% concentration of direct hyaluronic acid, which is (oddly enough) rare—as many formulas contain only Sodium Hyaluronate, the sodium salt of HA. ($60, NIOD)

Skinceuticals, HA Intensifier

Unlike many hydrating serums, which work to add hyaluronic acid to the skin, Skinceuticals most recent innovation works to boost the skin’s naturally occurring HA. Using a blend of pure hyaluronic acid and botanical extracts from purple rice and licorice, HA Intensifier boosts the skin’s HA levels by 30%, leaving the complexion plumped—and even helping (if temporarily) fill in lines and wrinkles for a younger appearance. ($98, Dermstore)

Patyka, Advanced Plumping Serum

This ultra-chic French brand (found in chic Parisian pharmacies) is a treat to find here in the States, but fortunately, Credo Beauty carries the line. This serum combines pure and botanically derived hyaluronic acid. Wakame extract helps promote the skin’s creation of collagen and elastin. ($110, Credo Beauty)

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