This Popular Serum Ingredient Is A Hair Care Hero — It Can Save Your Dry Locks

At this point, plenty of skin care ingredients have made a splash in the hair care department (AHAs in shampoos, ceramides in hair growth serums, and the list goes on). But using a proper skin care serum on your hair? Now, that sounds iffy, if not wasteful. Who wants to give up a precious product if it's not going to have the same benefits for your strands? 

Well, don't knock it till you try it—or check out this TikTok user who already did. In the video, she repurposes a cult-favorite serum and rakes it through the lengths of her hair. "After only two days, I saw and felt a major difference," she explains. And after a full, two-week experiment, her hair "feels so soft and is way more manageable." What's this secret ingredient, you wonder? Oh, it's hyaluronic acid. 

Hyaluronic acid is a humectant, meaning it has the ability to attract water to the surface of the skin and hair, as well as deliver hydration to the deeper layers. (And in case you haven't heard: Hyaluronic acid can hold 1,000 times its own weight in water1.) Chances are you rely on other humectants in hair care—ever tried a honey hair mask?—so consider hyaluronic acid another top choice to ramp up hydration. 

In fact, plenty of leave-ins, shampoos, and stylers include the ingredient in their formulas already—hyaluronic acid for hair is not a new concept. But from this TikTok experiment, it seems using a proper skin care serum can be just as effective, if you can spare a few drops. 

"HA lives in my shower for the face and hair," says board-certified internal medicine physician and skin care expert Zion Ko Lamm, M.D., in a duet video. If you have dry, frizzy, brittle, or damaged locks, she considers it a worthy addition to your routine (she typically uses it as a pre-shampoo or leave-in treatment). Best part? Like Lamm, you can streamline your routine and keep one vial on hand for your skin and hair—both will drink the HA right up. 

In the video, you'll see that the user applies her serum on damp hair as a leave-in treatment. A solid idea, considering hyaluronic acid pulls in water from the environment; so if you don't provide the water, HA will still do its job—it might just pull water from your hair shaft instead of the surrounding air, which can leave it straw-like. She uses The Ordinary's Hyaluronic Acid 2% + B5 (the added panthenol is extra moisturizing), but here are 15 more hyaluronic acid serums to browse—we adore them all.