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 water.) 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.
The only caveat to note is that hyaluronic acid doesn’t exactly seal moisture into the strand. It helps draw in moisture from the environment, yes, but as Lamm says: “It does not take the place of hair oils.” You’ll still want to lock in all that water with an occlusive product, or the precious hydration can seep out, and your hair may become even more limp and dry than before.