Hyaluronic acid is a humectant that’s usually marketed as being able to hold a thousand times its weight in water - which is debatable, but more on that later. It occurs naturally in the skin where it helps give skin its structure and keeps it plump and hydrated. Like collagen and elastin, hyaluronic acid also decreases in our skin as we age, making ageing skin more susceptible to volume loss, dryness, sagging, and wrinkles.

In cosmetics, hyaluronic acid tends to be used in one of two ways: topically, or as in injectable - think dermal fillers, but in this post I’ll limit my discussion to its topical use. Two popular myths around its topical use abound:

• Myth 1: Hyaluronic acid is an exfoliant - people assume this because of the word acid in the name.

• Myth 2: Hyaluronic acid is an anti-ageing ingredient.

Both are not true - hyaluronic acid is a humectant, i.e. a substance that helps the skin hold on to water. While essential for skin health when inside the skin, its molecules are too large to be absorbed when it’s applied topically. Topical application can at best, hydrate the skin’s surface so it appears plumper, and fine lines get smoothed over - but the effect is temporary.

Smaller molecules of hyaluronic acid do exist, and while they are able to go relatively deeper into the skin, they don’t bind as much water. However, even low molecular weight hyaluronic acid isn’t able to penetrate too deep and only a small fraction tends to make it to the base of the epidermis. Unlike molecular weight hyaluronic acid, low molecular weights of the ingredient have also been associated with skin irritation, where the smaller the molecule, the greater the irritation. And they tend to be especially problematic if your skin barrier is compromised.

A number of people who’re using hyaluronic acid and have a “good” skincare routine but still have skin irritation, see marked improvement once they cut the ingredient out. As Harper’s Bazaar nicely summarises:

“Editors and Redditors alike have written about the redness and dryness they believe to be caused by topical HA. Instagrammers and influencers have eliminated it from their routines, with impressive results. The Mixed Makeup Facebook group recently held an “HA-free” challenge, with hundreds of comments detailing individual HA sensitivities and reporting improvements. One-star reviews of popular HA serums point to extreme irritation, beauty brands have issued usage warnings for their HA-laced products, one medical-grade HA ointment advises patients that “prolonged use may give rise to sensitisation phenomena,” and hyaluronic acid injectables are increasingly associated with late-onset inflammation.

And here’s where things get really interesting. I mentioned in the beginning that hyaluronic acid is marketed as being able to hold up to a thousand times its weight in water. This is true of the version of the substance that’s in our bodies - owing to its very high molecular weight and large molecular volume - but there’s no evidence to prove that the hyaluronic acid found in cosmetics is able to do that. The Stanford Chemicals Company, a hyaluronic acid manufacturer, states that topical hyaluronic acid has limited ability to retain water, and this ability also depends on the size of the molecule in question. And according to the case files of a lawsuit filed against Peter Thomas Roth’s Water Drench line, “This outlandish claim [that hyaluronic acid can hold up to a thousand times its weight in water], is entirely unsupported by science. Published data from actual studies by real chemists establishes that hyaluronic acid binds a small amount of water, equivalent to about half the weight of the hyaluronic acid, or between 9 and 19 molecules.”

What About Sodium Hyaluronate?

Often when you find hyaluronic acid advertised on a product, the ingredients list contains sodium hyaluronate instead. Sodium hyaluronate is the salt form of hyaluronic acid and is also found naturally in the body. In fact, in the human body, hyaluronic acid tends to exist as sodium hyaluronate.

Sodium hyaluronate exhibits similar properties as hyaluronic acid. However, it’s more readily absorbed into the skin. It’s also less prone to oxidation and able to maintain a longer shelf life. Like hyaluronic acid, it’s also available in different molecular weights, where heavier weights deliver surface hydration and lower weights are able to go deeper into the skin.

The Verdict

Hyaluronic acid has become an extremely popular humectant. Anyone moderately interested in skincare is aware of what it is and it’s popping up in products everywhere. However, hyaluronic acid falls short of all the hype it gets for several reasons.

• Evidence doesn’t support the claim that when topically applied, it is able to hold up to a thousand times its weight in water.

• High molecular weight hyaluronic acid - the good kind - simply sits on top of your skin. There’s also evidence that hyaluronic acid results in skin dehydration. A 2018 study funded by Estée Lauder found that in humid environments it made the skin look temporarily hydrated but actually had the opposite impact and increased the rate of water loss through the skin. .

• Low molecular weight hyaluronic acid can go deeper but is associated with skin irritation and the lower the weight, the higher the potential for irritation. A study in 2016 also found that low molecular weight hyaluronic acid also increased water loss by over 55%

It’s not all bad news though and there is evidence to suggest that hyaluronic acid aids in wound healing. As a humectant though, I don’t believe that it’s the gold standard that it’s made out to be. Several other wonderful options exist. Here are some of my favourites:

• Glycerin. Glycerin is also found naturally in the skin. It’s an extremely popular humectant in skin care because it’s a fantastic moisturizer for all skin types, especially for dry, or dehydrated skin. It’s low molecular weight allows it to penetrate into the deeper layers of the skin to provide lasting hydration. Glycerin also doesn’t pose any risk of irritation even at very high concentrations and in fact, helps soothe irritated skin and reduces skin redness. In addition to providing hydration, it strengthens the skin barrier and protects the skin against environmental stressors and harsh ingredients like sodium lauryl sulfate. It also helps facilitate the skin’s natural exfoliation process.

• Panthenol. Panthenol, or provitamin B5, is a humectant and an emollient - a substance that seals cracks in the skin, thus helping reduce water loss and blocking the entrance of irritants. Panthenol moisturises the skin and helps it stay soft, supple and elastic. It is also anti-inflammatory, aids in wound healing and helps repair the skin’s barrier. It is also extremely well tolerated and helps reduce irritation.

• Urea. Also known as carbamide, urea is naturally found in the skin and makes up 8.5% of the skin’s natural moisturising factor. Like glycerin, urea also has small molecules that are easily absorbed into the skin’s deeper layers of the skin and help provide lasting hydration. The level of urea in our skin also decreases as we age, making us more susceptible to skin dryness. Urea levels are also significantly reduced in dry skin conditions like eczema and psoriasis.Topically applied urea successfully tops up the skin’s own urea stores, making it an effective treatment for dry skin and eczema, and has also been shown to reduce the skin’s susceptibility to irritants such as sodium lauryl sulfate (SLS). Lastly, and perhaps most importantly, urea has also been shown to kill acne-causing bacteria and inhibit the growth of the fungus that causes fungal acne.

If You Still Want To Use Hyaluronic Acid...

If you still want to try incorporating hyaluronic acid into your routine, or if you’ve been using it already and feel like it works for you, make sure that you use it right. Don’t use it if you’re young and your skin is already functioning well. But if you’re not, and are looking to try it for skin hydration, here’s how to use it.

Look for products that have a maximum concentration of 1% - in fact, lower concentrations of up to 0.5% might be better. Higher percentages can dehydrate the skin, as discussed earlier. Give preference to higher molecular weights and don’t use more than one product with the ingredient and avoid using it in dry climates. Apply it on damp skin and follow up with an occlusive moisturiser to seal in hydration.

And of course, why try applying it topically at all when you can instead focus on trying to boost your skin’s own production of the ingredient. Evidence suggests that oral hyaluronic acid supplements help relieve the symptoms of dry skin while ingredients that increase skin cell turnover, like glycolic acid, lactic acid and salicylic acid, found in products like our Salicylic Acid Cleanser and Salicylic Acid Emulsion, also help increase the skin’s own production of hyaluronic acid.