chemical formula of urea on a blackboardYouthful, hydrated, wrinkle free, skin.

The type that has a lovely luminous glow.

It’s the holy grail of skin care.

Well what if I told you, the key to super healthy skin is hydration.

A dehydrated skin causes horizontal lines to appear.

The types of lines that lead to deep seated wrinkles, especially if not treated correctly.

That’s right, something as simple as keeping your “skin plump and moist, can ward of premature ageing“.

But shhh there is one little beauty “secret that not to many people know”.

Urea, which in my opinion, is one of the most effective moisturising ingredients in cosmetic chemistry.

Urea’s role within the skin is to maintain a healthy moisture balance, keeping it soft, supple and youthful, bringing much needed relief to a dry skin.


Urea is a humectant referred to as hydroxyethyl urea, not to be confused with the preservative sdiazolidinyl urea and imidazolidinyl urea, which I discuss in more detail below.

A healthy skin will typically contain 28 micrograms of urea per square centimetre, a dehydrated, dry skin can see a reduction of as much as 50% and those with eczema as much as 80%.


In order to understand how urea works, it is important to understand the skins structure.

Your outer layer of skin the stratum corneum is made up of corneocytes, an intercellular cement which has a high resistance to many chemical agents.

Inside the corneocytes is a natural moisturising factor (NMF), a mixture of substances that regulate the level of moisture on our skin surface, by binding water molecules.

Urea is a natural component of our skin’s tissues and makes up 7% of our natural moisturising factor, which decreases with age.

Whilst applications of emollient and occlusive ingredients coat the skins surface creating instant moisturisation it is only a temporary fix, it won’t improve the skins ability to create and hold water, like urea does.

When it is applied to the skin it penetrates the stratum corneum, where it readily absorbs and retains water, thus increasing the capacity of the skin to hold moisture and rehydrate.


Dry skin is a result of lack of oil and water in the outer layer of skin the epidermis, skin becomes scaly, cracked and itchy.

Moisture is normally retained in the stratum corneum by a surface film of oils (sebum), broken-down skin cells and natural water holding substances, urea is one of the water holding substances, the others are lactic and amino acids.

We know reduced levels of urea leads to a lower water-binding capacity within the skin, which in turn leads to roughness, tightness, flaking, and irritation.

Research has also found a link between severe dry skin conditions such as ichthyosis, psoriasis and eczema maybe a result of drastically reduced amounts of urea in the stratum corneum.


Urea is a substance that readily absorbs water, it also has a very high water content, which helps to reduce the amount of water lost through the skin.

On a molecular level urea modifies the structure of amino chains and polypeptides within the skin, which is important for helping to moisturise our delicate tissues.

Research has found a direct correlation between water content and the amino acid content of our skin, basically the more dehydrated and dry the skin is, the lower its share of dissolved amino acids.

Improves Barrier Function
One of Urea’s many benefits, is that it helps to accelerate the skins cellular renewal process.

The really great thing about this, is that it strengthens the barrier function of the skin, helping to keep it youthful and healthy.

In the article understanding the acid mantle, I discuss the importance of having a strong barrier function, and how this creates a stronger resistance against potential irritants.

Natural Exfoliant
Urea works in synergy with ingredients that create the molecular structure of the skin, such as lactic acid.

Combined, these two ingredients actively work to remove dead skin cells and substances from the horny layer, improving cellular turnover in the epidermis, helping to dramatically improve the water binding ability of the skin.

Possible Anaesthetic
Urea has another interesting profile, it can create a local anaesthetic affect on the skin.

This is really useful in helping to reduce cycles of inflammation and flare-ups, making it my product of choice for sensitive skin conditions.

Studies have found, one of urea’s key roles, is to increase the skin permeability of certain skin care ingredients, working as a vehicle for other performance ingredients, encouraging them to penetrate the epidermis easily.

Natural Moisturiser
Often a dry skin is due to a reduction of urea in the skins delicate tissues, which can lead to tightness and flakiness; because of urea’s natural moisturising factor, it can offer instant relief to dry skin.

Personally I have seen some great results from urea on my clients who suffer from extremely dry, cracked skin, especially on the hands and feet.

The Naked Truth
Urea is often referred to as carbamide the primary organic solid of urine, this is waste that has been produced by the body after it metabolises protein.

Thankfully, the urea used in the cosmetic industry is from synthetic sources and not animal derived, it is formed from ammonia and carbon dioxide, and can be produced in either a solid or liquid form.

As discussed earlier there are three forms of urea found in personal care products, hydroxyethyl, diazolidinyl and imidazolidinyl urea; often people get confused by these, but they are in fact two completely different ingredients.

Diazolidinyl Urea andimidazolidinyl urea are antimicrobial preservatives used in the skin care industry. They are used to protect personal care products from bacteria, yeast and mould, they do get a lot of bad press as a preservative, due to the fact that they are proven formaldehyde releasers.

Hydrovance, inci name hydroxyethyl urea is a potent humectant and considered safe as a cosmetic ingredient.

I do hope I have gone some way to answer your questions on what is urea, I appreciate that a dry skin is a really frustrating skin type to treat, simply because it causes so many conditions within the skin:

  • Dehydration due to a lack of water
  • A lack of a protein referred to as Filiagrin
  • Dryness because of a reduction in ceramides and moisturising lipids 

If dryness is an issue for you, I have put together a complete section on dry skin, that you may find useful.

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