Dry Skin vs. Dehydrated Skin

Posted by Dr. Natasha Ryz on

You may have experienced dry skin or dehydrated skin during the cold, winter months.

Dry or dehydrated skin appears dry, rough, and may scale and flake. It may also show premature signs of aging, like surface wrinkles and loss of elasticity.

Dry skin and dehydrated skin both develop from a lack of water and water-holding substances in the skin, called humectants. However, dry skin is also lacking fats, that are found naturally in the skin, and these essential fats can be re-introduced through skincare products and dietary changes. 

What is Dehydrated Skin?

Dehydrated skin is skin that is lacking water and water-holding substances, called humectants.

Dehydrated skin appears dry, rough, and may scale and flake. It may also show premature signs of aging, like surface wrinkles and loss of elasticity.

Dehydrated skin can happen to anyone, regardless of skin type — if you have dry, oily or combination skin, you can still experience dehydration.

Read more: What is Dehydrated Skin?

Dehydrated skin can be relieved with the use of moisturizers and humectants, including glycerin, hyaluronic acid and natural moisturizing factors.

Normal Skin Hydration

Water is essential for the normal functioning of the skin. 

The water content of skin is remarkably high - the epidermis (the outer skin layer) contains more than 70% water, while its outermost layer, the stratum corneum has been shown to contain ~15 - 25% water (Warner et al, 1988; Caspers et al, 2001; Caspers et al, 2003).

Adequate hydration of the stratum corneum serves three major functions (Fowler, 2012):

  1. It maintains plasticity of the skin, protecting it from damage.

  2. It contributes to optimum stratum corneum barrier function.

  3. It allows hydrolytic enzymes to function in the process of desquamation.

When the water content of the stratum corneum falls below 10%, scaling on the skin surface becomes visible (Rycroft, 1985).

The retention of water in the skin is dependent on:
  1. Natural moisturizing factors (NMFs) and other humectants (such as glycerol and hyaluronic acid) to attract and hold onto moisture.
  2. Intercellular lipids (fats) that form a barrier to prevent transepidermal water loss (TEWL) (Verdier-Sévrain et al, 2007). 

What is Dry Skin?

Dry skin is uncomfortable - it is overly tight, dehydrated, rough, and may flake and itch. Dry skin is a seemingly simple condition that has a wide spectrum of symptoms - from mild dryness and flaking to severe itching, redness and pain.

Dry skin is skin that is lacking water, humectants and fats. Humectants absorb and hold water, while fats coat the skin and seal in moisture. When there is not enough water, humectants or fats, skin barrier disruption can occur, further worsening symptoms of dry skin.

The following contribute to dry skin:

  • lack of water in skin

  • lack of water-holding substances called humectants (glycerin, hyaluronic acid, natural moisturizing factors)

  • lack of epidermal lipids (ceramides, fatty acids, cholesterol)

  • lack of sebum (triglycerides, wax esters, squalene)

Sebum is an oily, waxy substance produced by your body’s sebaceous glands. Sebum coats the skin, seals in moisture, and protects your skin from getting too dry. When there is not enough sebum, skin appears dull, rough and flaky, and skin feels overly tight, itchy and uncomfortable.

Dry skin is very common, and can occur for a variety of reasons. You may have naturally dry skin. But even if your skin type is normal or oily, you can still develop dry skin from time to time. Dry skin can affect any part of your body.

Read more: What is Dry Skin?

Dry skin is often relieved with the use of moisturizers, and some lifestyle modifications, such as using a humidifier, avoiding harsh cleansers, and supplementing the diet with essential fatty acids.

Normal Skin Lipids

The surface of your skin is covered by a layer of protective lipids (fats), including epidermal lipids and sebum.

Epidermal lipids are released from keratinocytes (skin cells), and are a mixture of ceramides, free fatty acids and cholesterol. These lipids are released from skin cells and fill the spaces between the cells, like mortar or cement (Pappas, 2009).

Sebum is an oily, waxy substance produced by your body’s sebaceous glands and eventually released to the surface of the skin. Sebum is primarily made up of non polar lipids as triglycerides, wax esters and squalene. Sebum coats the skin, seals in moisture, and protects your skin from getting too dry (Pappas, 2009). 

Summary

Dehydrated skin is skin that is missing water and water-holding substances, called humectants.

Dry skin is skin that is lacking water, humectants and fats. Humectants absorb and hold water, while fats coat the skin and seal in moisture. When there is not enough water, humectants or fats, skin barrier disruption can occur, further worsening symptoms of dry skin. 

References

Dehydrated Skin Dry Skin Skin Science Skin Type Skincare

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