What Is… Hyaluronic Acid? We Reveal All About This Skincare Must-Have

Amy Lawrenson

Hyaluronic acid (HA): If you know about this molecule, you know it’s a must in any skincare routine. If you don’t, then you should know that it’s what keeps our complexions hydrated, giving our skin that plump, dewy look whatever the weather. Thing is, at this time of year, our complexion’s summer-induced glow heads off to hibernate. Rude. We have to keep rocking on through the dreary weather, though, so our glowing skin should too.

The trouble is that cold weather and indoor heating suck moisture from your skin. On a cold day, moisture evaporates from the epidermis while a heated room dries your complexion out further. Since hyaluronic acid is so good at drawing water back in, it makes sense that now is a good time to incorporate a hyaluronic acid–based product into your routine. Trust us: It’s like a tall glass of water for your face. Keep scrolling to find out more about this hydrating molecule, what you need to look out for when shopping for it, and the best products out there that you can shop right now.


Contrary to its name, hyaluronic acid is actually a polysaccharide, a large sugar molecule. “It’s found naturally within our bodies, 50% of it within our skin, and its highest concentration is inside the eyes and joints. It holds moisture in the spaces between the cells of our skin, helping it to stay plump. Babies’ skin contains very high levels—it really is the source of ‘baby soft’ skin,” explains Dia Foley, vice president of sales and marketing at Indeed Labs.

Applied topically, “hyaluronic acid helps soften fine lines, making the skin appear firmer and smoother while also helping to even out any dry patches,” adds facialist Abigail James. “And as if you needed any other reason to give it a go, the moisture that HA carries helps to add volume to your skin cells, giving them a plumper appearance.”

Unfortunately, as we age, our body’s ability to produce hyaluronic acid dwindles. Frances Prenna Jones, MD, explains, “Our natural hyaluronic acid levels start to deplete age 26 and are very low post- and peri-menopause. At age 16, it sits within our skin in a nice even mesh-like framework attracting nice, even amounts of water around itself, hence keeping our deep dermis and dermis plump and hydrated and healthy.”


Interestingly, hyaluronic acid has a counterpart named sodium hyaluronate. “Sodium hyaluronate is the salt form of HA and is a water-soluble salt that holds 1000 times its weight in water,” Stacked Skincare founder Kerry Benjamin says. “Ingredients are in salt form because they are more stable and less likely to oxidize.”

Both forms are used in beauty products, but marketers refer to both as “hyaluronic acid” even though there are some key differences. Namely, sodium hyaluronate has a much lower molecular size, which allows it to penetrate the skin better. “In skincare, there is a formula determining how well products penetrate skin using the molecular weight,” Benjamin says. “The lower the weight, the more it can penetrate.”

For hyaluronic acid to really penetrate the skin’s surface, it actually has to be bioengineered to have a much lower molecular weight.

When applied topically, hyaluronic acid works as a humectant to draw moisture into the top layers of the skin. Unlike retinol or vitamin C, which tends to come in different percentages, hyaluronic acid comes in varying weights.

“Low–molecular weight HA is what you are looking for in skincare, as higher molecular weight HA cannot penetrate the skin’s protective barrier,” explains Maryam Zamani, MD. “Studies have clearly shown that the smaller the molecular weight of the active, the greater the skin penetration and the greater the skin hydration,” she adds.

Ideally, you want a lightweight product like a serum to carry the HA as opposed to a heavy cream, which could hinder absorption. Although, Zamani caveats this by saying, “The smaller the particle size, the better the penetration. But if a cream uses nano-HA, for instance, the penetration will be better than say a serum with a heavier HA particle.”

There is still much debate around how deep topical hyaluronic acid can penetrate the skin. Skinceuticals launched H.A. Intensifier (£83), which actually triggers the skin’s production of hyaluronic acid. Used topically, it can tackle crow’s feet, nasolabial folds (around the mouth) and the marionette lines at the corners of the mouth.

Hyaluronic acid can also be found in fillers like Juvederm and Restylane. Jones administers hyaluronic acid into the skin via deep mesotherapy, which she believes is the best way to reap the effects of deep down hydration.

Keep scrolling to see the hyaluronic acid products these experts recommend.

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