Of all the hydrating ingredients out there, none have reached the same level of fame as hyaluronic acid. Even those who aren’t skin-care die-hards know what it is — or, okay, have at least heard of it — as its ability to hold 1000 times its weight in water makes it a favorite of product formulators in everything from essences to overnight masks.But even with its solid reputation, there have been some rumors about certain drawbacks to hyaluronic acid — that it’s drying in certain climates, for one, or that it could draw bacteria into the skin. To help you separate HA fact from fiction, we put together this end-all, be-all guide to all things hyaluronic acid.It’s Basically a SpongeThink of hyaluronic acid as nature’s moisturizer. “Skin relies on hyaluronic acid’s ability to draw water to itself like a sponge,” explains Rita Linkner, MD, a dermatologist at Spring Street Dermatology in New York City. By pulling in hydration, it keeps your skin cells operating smoothly and efficiently. And though it’s best known for its ability to hydrate skin, soften, and minimize lines and wrinkles, it can also help with wound healing, says Dr. Linkner. Our skin loses 1.5 cups of water a day on average, so it’s important to infuse skin with moisture throughout the day. The Watermelon Glow Ultra-Fine Mist is packed with hyaluronic acid—just spritz it over your face every two hours (pro tip: if you have dry skin, hold it closer to your face) to keep skin plump and healthy.It Draws Moisture (and Only Moisture) Into SkinOne myth making the rounds is that if you apply hyaluronic acid during a flight — generally a good idea, seeing as the plane air is notoriously drying — it can draw in bacteria along with moisture. “Hyaluronic acid can’t draw bacteria into the skin,” says Dr. Linkner. “This is just not its mechanism of action.” Translation: It can’t draw pollution, germs, bacteria, or anything floating around in the air into your skin.The Body Naturally Produces ItThough it’s usually associated with skin care, hyaluronic acid (which also goes by sodium hyaluronate on ingredient lists) is produced throughout the body. “Hyaluronic acid is a sugar the body makes naturally,” Dr. Linkner. Hyalos, the derivative of the word hyaluronic, means “glass” in Greek, which is what hyaluronic acid in its raw form resembles, she adds. And as glass skin is the goal of any good skin-care routine, hyaluronic acid definitely deserves a place in yours. For beginners and experts alike, we recommend Glow Recipe Watermelon Glow Pink Juice Moisturizer. It’s spiked with amino-acid rich watermelon extract and a huge helping of hyaluronic acid, all in a lightweight, cooling emulsion that gives your skin a juicy, plumped-up dewiness. It’s perfect for every skin type, age, weather, and routine.It Degrades With AgeWhile you naturally produce hyaluronic acid, research shows that the amount of it present in your skin (particularly in your epidermis, the outermost layer of skin) takes a nosedive over the years. This gradual loss — along with that of collagen and elastin — makes skin feel dry, look slack, and become prone to lines and wrinkles. Sun exposure — surprise, surprise — doesn’t help, either. It breaks down hyaluronic acid, leading to moisture loss in the short-term, too.It Comes in Different SizesNot all hyaluronic acid molecules are created equally. In fact, hyaluronic acid molecules can come in five molecular weights, or sizes. Smaller particles can easily sink into the deeper layers of skin, where they help it maintain its moisture content for long-term hydration. The larger particles, on the other hand, stick closer to the surface, where they create softer, firmer skin immediately. A formula that contains at least a few different sizes of hyaluronic acid is ideal, as it keeps skin hydrated at every level. If you want to get the most out of this amazing ingredient, Leegeehaam (LJH) Grow Hyal B5 Toner offers all five sizes so you get literally all the hydration.Pair It WiselyThe internet is full of rumors, and one that has caught traction lately is that in dry climates, hyaluronic acid can actually dry skin out when applied. Here’s the thinking: Since there’s no moisture to pull in from the air, it draws moisture out from deeper layers of skin instead.That’s just not how HA functions, says Dr. Linkner. That said, in super-dry locations, it will evaporate much faster on the skin. To prevent that dissipation, apply an occlusive ingredient that will trap the moisture in the skin so it can do its job plumping, healing, and hydrating your complexion. Plant oils are fab for this moisture-sealing action because they work on the surface of the skin to smooth and moisturize as well.Because we want to make sure you get the most out of its hydrating action, here are the perfect pairs for your hyaluronic serum. In the a.m., apply Jullai Super 12 Bounce In Oil Cream — it’s enriched with olive and avocado oils, plus the brand’s signature Super 12 Complex of antioxidant fruit, veggie, and flower extracts. In the p.m., Glow Recipe Avocado Melt Sleeping Mask is a total star thanks to its avocado oil, butter, and fruit base that work together to seal in hydration.As if you needed another reason to add one of these to your routine, Dr. Linkner says that an extra layer of moisture can offer even better results. “Hyaluronic acid can draw more water molecules from the moisturizer to provide a longer-lasting, more plumping effect,” she suggests. It’s a win-win!