Hyaluronic Acid - What Is It And What Does It Do?

UPDATED: 19/3/20

By now, you’re well accustomed to hyaluronic acid. In the last while, the most popular of the cosmetic skincare brands have started to include it in their formulations, meaning that no matter your budget, you can fit the wonder that is HA into your routine. This is a good thing, of course, but you should know when to use it, when not to use it and which types of HA do what.

In the simplest of terms, hyaluronic acid is an ingredient that pulls moisture to it. The nerdie term is “humectant”. Humectants are a key type of hydrating ingredient that you will find in nearly the majority of skincare products – glycerine is a humectant, urea is a humectant… even honey is a humectant. 

Hyaluronic acid is better than these guys – it’s the Beyoncé of humectant ingredients, as it can bind more than 1000x its weight in water to it. Wow. I can’t imagine carrying 1000x my own weight. When many see the word “acid”, they think exfoliating acid. Hyaluronic acid ain’t an exfoliating acid so it’s not going to help you to slough off dead skin cells (or possibly irritate your skin).

Hyaluronic acid and the skin

Hyaluronic acid is a natural ingredient in the sense that it naturally exists in the skin already. Yes, indeed, one of my all-time favourite skincare ingredients is being manufactured throughout your body as we speak. Hyaluronic acid is made throughout the body and in the dermis, and it is part of a number of processes when it comes to the skin – obviously, it’s important for hydration but it is also involved with wound healing (tissue repair).

Bad news if you’re not Benjamin Button – as we age, our rate of HA production decreases and decreases so our skin struggles to hydrate itself as easily as it used to. This is why it’s considered to be an anti-ageing ingredient, even though it’s beneficial for all ages.

Hyaluronic acid for skin: what does it do?

Topical hyaluronic acid, due to its moisture-pulling capabilities, can give the skin back moisture. Realistically, if your skin isn’t at peak health (ie. you’re not using a routine that replenishes your barrier, protects your skin from pollution and light-related damage, you’re not getting enough omegas internally etc.), your skin may not be holding enough of its own moisture. If you’ve got the right type of hyaluronic acid (more on this in a sec) in a serum, it can penetrate into the skin and hydrate it at lower layers which is something that moisturisers can’t do due to the size of their molecules.

Other forms of hyaluronic acid can plump up the uppermost layers of the skin, giving you the gift of instant youth. This is why it is known for its use in fillers! Not sold yet? It also works as an antioxidant to protect your skin from the free radical damage that can age the skin faster.

Forms of hyaluronic acid in skincare

As I said, we can pop down to our local supermarkets and get something with hyaluronic acid in it. However, there are different forms that do different things and some may be considered more beneficial than others.
  • High molecular weight hyaluronic acid – the molecules of HMW hyaluronic acid are larger so they do a great job of sitting in the uppermost layers of the skin and swelling it but you won’t be getting moisture drawn deeper into the skin... This will be listed on products as hyaluronic acid

  • Low molecular weight hyaluronic acid – this is hyaluronic acid (HMW hyaluronic acid) whose molecules have been made into fragments that penetrate into the skin easier due to their smaller size… better penetration means it can get deeper into the epidermis – often, when a product says it has low molecular weight HA, it's sodium hyaluronate (explained below)

  • Sodium hyaluronate – sodium hyaluronate is the salt of hyaluronic acid that has the same humectant capabilities but can have a smaller molecular size, so like with low molecular weight HA, it can penetrate into the skin deeper... Sodium hyaluronate is easier to formulate too

  • Cross-linked hyaluronic acid – cross-linked hyaluronic acid can remain on the skin for longer as it is more resistant to the hyaluronic-gobbling enzyme found in our skin (hyaluronidase)… its effects are longer-lasting

Is sodium hyaluronate better than hyaluronic acid? Yes and no. It’s better as it hydrates the skin deeper but it may not plump up the uppermost layers to the same extent.

Some serums will have a bundle of different forms of hyaluronic acid. IMAGE Skincare’s Ageless Total Pure Hyaluronic Filler contains 6 forms of HA including pure, high-molecular weight hyaluronic acid, sodium hyaluronate and cross-linked hyaluronic acid. This means that it’s hydrating deep down whilst popping out dents on the surface of the skin at the same time.


Skingredients Skin Veg contains a low molecular weight of hyaluronic acid in the form of sodium hyaluronate, as well as oodles of botanically-based antioxidants! This hydrating, anti-ageing serum is particularly loved by MUAs, and works perfectly as part of your everyday skincare routine. 

Who is hyaluronic acid best for?

Dehydrated skin

As it is a hydration-blaster, it slays dehydration. It is Buffy the Dehydration Slayer.

Oily & congestion-prone skin

As a non-oily hydrator, it does wonders as a hydrating product for those with oily or spot-prone skin as it doesn’t clog pores and doesn’t leave a greasy layer on the skin. 


Mature skin

Hyaluronic acid, specifically high molecular weight hyaluronic acid, gives mature skin back the bounce and elasticity it may have lost naturally. Moisture slightly swells the uppermost layers of the skin so fine lines and wrinkles will look instantaneously less noticeable.

Those with impending nuptials

Brides & grooms can benefit mahoosively from using hyaluronic acid in the run up to and day of their wedding. It will do more than a skin-perfecting foundation will ever be able to do!

When to avoid hyaluronic acid

If you have very dry skin, it might not be enough on its own. A product that contains hyaluronic acid with something lipidic (read: oily) in there too would work for you though! 

If you’re in a dry climate (ie. the desert, Texas, Vegas, or it is Winter?), hyaluronic acid can actually flip its role and dehydrate the skin.


Well, as it draws moisture from the air, a lack of moisture in the air can lead to it pulling moisture outwards from the lower layers of the skin. Some find that topping their HA serum with a thicker moisturiser can stop this from happening. Most people with very sensitive skin don’t have issues with serums that contain hyaluronic acid and only a few other ingredients – HA itself tends not to be irritating to even those with “princess skin”.

Is hyaluronic acid vegan?

The simple answer is that it usually is nowadays. With brands focusing on ensuring that the majority of their products are suitable for vegans, the HA found in products is primarily not from animal sources. Always check the product or the brand of HA you're using to ensure that it is not animal-derived.

Top nerdie tips on hyaluronic acid

Mix it with your lip balm, your body products and you can even pop some into your hair. I just put a little bit into the ends of my hair to freshen it up, everyone knows the struggle of dry ends. There are lip balms that contain hyaluronic acid too, lthat contains hyaluronic acid microspheres! 

Keeping your skin hydrated

Although hyaluronic acid is an all-rounder, everyone's skin needs different things. Come and have an online skin consultation with one of our expert Nerds or Nerdettes, gain access to our store and tonnes of exclusive content...