[Guide] Hyaluronic acid: the benefits in skincare. | The definitive guide
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Hyaluronic acid: the benefits for the skin - The definitive guide.

If you formulate skincare products for a living, but also if you just like to research ingredients before making a purchase, you probably face an overwhelming number of information.

FACT: There’s a plethora of cosmetic ingredients.

How do you decide what to focus on?

There’s no univocal answer to this question, but I can share what I do.

I focus on ingredients that 1) have scientific evidence supporting their action and 2) have a long history of usage with relatively no side effects.

This is why I ALWAYS include hyaluronic acid in my own formulations and in the formulations I develop for my clients.

Hyaluronic acid is a staple ingredient in skincare. You can find it in serums, eye creams, lotions, and even rinse off products.

As a cosmetic chemist I know how some ingredients get the hype and then disappear after a few months.

On the other side, there are ingredients that never lose their popularity.

 Hyaluronic acid is one of these winners. It’s a safe and effective ingredient. SAFE as it has a low irritation potential. EFFECTIVE as several scientific studies confirm.

If you're interested in discovering the amazing properties and skincare benefits of hyaluronic acid, keep on reading.

What is Hyaluronic acid?

From a chemistry stand point, hyaluronic acid is a polimer. 

A polimer is a structure that consists in a large number of similar units bonded together.
In the case of hyaluronic acid the units are glucuronic acid linked to N-Acetyl- Glucosamine.

Hyaluronic acid is usually sold as sodium salt (sodium hyaluronate-powder), which releases hyaluronic acid in water.

The most important take home message is that Hyaluronic acid comes in different forms which have different molecular weights.
In fact, polymers have different weights, just like people. Molecular weight is determined by the number of units present in the polymer. The more, the heaviest.

  • High molecular weight HA ( 1.5 MDA). DA means Dalton which is a unit measure for weight. It's the equivalent to oz for very small weights such as molecules.
  • Low molecular weight HA (50kD).
  • Extra Low molecular weight HA.
  • Crosslinked HA (rare in skincare).

In the skincare industry, hyaluronic acid is considered a *humectant moisturizer.* It’s also useful for scars and wound healing.

When I write about Hyaluronic acid on Quora, people ask me all the time why I'm a strong proponent of high molecular weight and why I did not include medium or low molecular weight hyaluronic acid in the serum I developed.


How does Hyaluronic acid work?

Hyaluronic acid is naturally present in the skin.
However, its content decreases with aging, and the most visible effects are *the loss of facial skin hydration, elasticity and volume, which are responsible for wrinkles.* This is how HA works as anti-age agent.

If you’ve been following my content, you should know that I’m always radically transparent; therefore, I must point out that *the anti-age activity has not been proven in clinical trials yet.

Over the last few years, HA has been widely used as a biomaterial to develop dermal fillers (DFs), which are medical devices that, injected into or under the skin, restore lost volumes and correct facial imperfections such as wrinkles or scars. This is the most effective way to take advantage of HA anti-aging properties.

Does this mean that skincare products based on HA are just a waste of money?

Actually, hyaluronic acid serums , when properly formulated, are among the simplest yet most effective products.

Here’s why.

HIGH MOLECULAR WEIGHT HA works as a *film-forming polymer:* it reduces water evaporation, with an occlusive-like action. Unlike other occlusive agents, though, it creates a cosmetically elegant film , rather than an oily thick and sticky barrier. The feel is light on the skin, the serum promptly absorbed so that you can apply a moisturizer right after it. 

 This is the main advantage of using it.

On the other hand,*MEDIUM and LOW MOLECULAR WEIGHT HA*mainly work by binding moisture from the environment meaning they act as humectants rather than moisturizers. In some cases, this capacity may reverse HA’s expected hydrating activity as at a high concentration, HA may even extract humidity from the skin, leaving it even more dry.

Furthermore, as this brilliant article explains in details, medium and low molecular weight HA are pro-inflammatory. These two forms of hyaluronic acid should be avoided especially when the skin barrier is already damaged and fragile.

The importance of the skin barrier.

Do you know what determines the overall appearance of the skin?

Water content.

"Barrier function,  skin elasticity, and resistance are all dependent on water content".

We all use moisturizers because we tend to have dry skin, right?

As we age, barrier function tends to become compromised. The worsening of the barrier function manifest itself with an increase in *TEWL* which stands for trans epidermal water loss. This basically means the skin loses more water than it is supposed to, thus becoming dry and dehydrated.

Hyaluronic acid is an humectant meaning it is able to draw water from the dermis (deep skin layer) to the epidermis (the portion of the skin that we can touch- the most external one).

This is why the immediate effect of using it a plumper and hydrated skin. 

Another approach to tackle dry skin is the use of creams that contain humectant ingredients; the most common humectants are glycerin, hyaluronic acid, sorbitol. urea, propylene/ butylene Glycol and its natural version propanediol.


However, when the skin barrier is damaged creams that only contain these ingredients not only can’t help, but they actually draw even more water from the skin, especially when used in very dry climates.

The best approach to tackle dry skin is the use of creams that contain *occlusive ingredients* (for example petrolatum a.k.a vaseline or lanolin). The problem is these creams are usually greasy, and therefore, not well tolerated, especially on the face. Furthermore, petrolatum and lanolin have raised health and environmental concerns.

The way these barrier creams work is by forming a hydrophobic (= water repellent) layer on the skin surface. This *mechanically* prevents water loss.

​Instead of improving the situation, they actually make it worse.

Emollient ingredients help with dry skin, too, by improving softness, smoothness, and elasticity. Examples of emollients are fatty acids and alcohols or *vegetable oils.*

Extra dry skin benefits from the application of both , creams and oils.

Where does Hyaluronic acid stand?

As stated above, hyaluronic acid is an humectant moisturizer ingredient. But we have seen not all hyaluronic acids are equivalent.
High molecular weight HA is the only form that work as both, *humectant AND occlusive.*

This is a huge advantage.

Using a product with high molecular weight hyaluronic acid allows you to have the benefits of occlusive ingredients without their downsides (“heavy” formulations that are tacky and greasy) AND an dramatic increase in moisture due to its humectant properties.

Skincare products based on hyaluronic acid- The benefits. 

HA represents a moisturizing active ingredient widely used in cosmetic formulations (gels, emulsions or serums) to restore the physiological microenvironment typical (and the look, of course) of youthful skin.
HA’s hydrating effect largely depends on its molecular weight.

If you start including Hyaluronic acid in your skincare routine, you’ll notice a *plumper, softer and smoother skin*.

However, please remember that the skin is an organ and skincare products are no magic bullet, no matter how good they are. If you don’t sleep enough, your diet is off , and you rarely exercise, nothing will work.
Sadly you’ll end up switching from one product to another without any improvement.

This is why some people claim hyaluronic acid actually made their skin worse.

Hyaluronic acid : skincare routine for dry skin.

dry skin

Avoid drying harsh cleansers. If it’s a face related issue, use micellar water or an oil based product rather than foaming cleansers. In particular, avoid all cleansers that contain sodium lauryl sulphate (SLS) and other anionic surfactants . These have an excellent cleaning and foaming power, yet tend to be aggressive. As a general rule, look at the foam. The more foam a product makes, the more aggressive it is.

Do not wash more than twice /day (face) and once / day body. If you don’t wear makeup, cleaning the face once /day is more than enough. If you feel you need to refresh it throughout the day, spray some water 

A great micellar water is the Bioderma Sensibio


In the morning , after you clean, apply a hyaluronic acid serum and layer it up with a moisturizer. The moisturizer should be very rich in ingredients such as Ceramides, urea, and cholesterol. An excellent moisturizer is the Clinique Dramatically Different lotion ($28 for 4.2 oz).


At night, before going to sleep apply a nightly moisturizer. The more occlusive, the better. So for instance even basic petrolatum will do. If you can’t tolerate Vaseline, these are 2 other options.

Remember that if you have dry skin you should limit alcohol intake and drink plenty of water.

By now you should feel quite enthusiastic about hyaluronic acid! 

​It should definitely belong to your skincare routine. 

Have questions? Leave them in the comments below.

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