What causes skin dehydration?

Woman drinking water
  • Water, just like air, is an element essential to our health.
  • Water accounts for approximately 65% of an adult’s total body weight.
  • Thus, a person weighing 70 kg is made up of around 49 litres of water, 15% of which are concentrated in the skin.
  • Water plays an essential role in the skin. The skin is a reservoir that other organs tap into. It facilitates exchanges with the exterior environment: water moves from the dermis to the surface by impregnating the various layers by diffusion.
  • This flow of water is called Transepidermal Water Loss (TEWL). Naturally protected by a hydrolipidic film on its surface, the horny layer (outer layer of the epidermis) curbs this evaporation process.
  • If this physiological barrier is impaired, TEWL speeds up, thus making the skin dry. Water in the dermis no longer circulates to the epidermis; the hydrolipidic film stops functioning properly.

All sorts of factors can cause dehydration

The skin is very sensitive to water deficiencies, that’s why it has a hydroregulation mechanism.

1) Skin hydroregulation

The skin is 70% water. Nearly 75% is located deep down in the dermis where it plays an important role in the skin’s resistance.

2 elements moisturise the epidermis:

  • static water, which is fixed,
  • and dynamic water, which circulates.

Hydroregulation achieves a balance between these two aqueous components and it alone guarantees the skin’s physical and functional integrity. Three main factors contribute to hydroregulation: NMFs (Natural Moisturizing Factors), lipids in the horny layer and aquaporins.

Water drops

2) NMFs (Natural Moisturizing Factors), hydroregulation factors

NMFs are molecules that can bind water within the horny layer; they are called humectants. The most commonly known NMFs are urea and lactic acid.

Other substances used in cosmetics have the same properties; these include glycerine and xylitol.


How can you tell the difference between dry skin and dehydrated skin?

Dehydrated skin is always a temporary condition that can be reversed with appropriate products.

It is an alteration in the superficial layer of the epidermis that lacks water. This lack of hydration disturbs the skin’s barrier function and leads to discomfort.

On the other hand, dry or very dry skin is a permanent condition that describes a particular skin type that is lacking both water and lipids.


Who is affected?

All skin types can become dehydrated in certain circumstances or during particular seasons.

Leave-on daily cleanser

Dehydrated sensitive skin

Aquagenium™ patent

Hydrabio H2O

The dermatological micellar water cleanses, removes make-up, moisturises.

For whom ?

Adults, Teens


Dehydrated sensitive skin

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Hydrabio Sérum

The concentrate that generates instant and lasting hydration.

For whom ?

Adults, Teens

Daily skincare

Normal to combination skin Dehydrated sensitive skin

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Hydrabio Gel-Crème

The smooth skincare generating hydration and intense radiance.

For whom ?

Adults, Teens