Biomimetic Skin Care

Is Dry Skin the Same as Dehydrated Skin? April 24, 2009

What is the difference between dry skin and dehydrated skin?

It is nearly impossible for the lay person to distinguish whether their skin is dry, or whether it is dehydrated. This is because both show similar symptoms: the skin feels tight and rough, often accompanied by a slight stinging or burning sensation. Yet the causes for these two conditions are completely different.

We speak of dry skin when there is a lack of natural oils. Our skin’s production of sebum changes a great deal over a lifetime, as illustrated in this graph by Dr.med. R.K. Achenbach:

Sebum Content of Ageing Skin

Dehydration, on the other hand, is a sign of a lack of moisture in the skin. A healthy epidermis has a water-content around 10%. Excessive moisture loss (TEWL or Trans Epidermal Water Loss) will cause the level to fall below 10%; the symptom is dehydrated skin.

Both sebum (oil) and water are essential for healthy, radiant skin. These two, combined with the NMF’s (natural moisturizing factors – e.g. sodium PCA, urea, lactates) ensure the skin’s moisture loss remains at a natural, healthy level.

Dry skin can be caused by various factors. An age-related decrease in sebum production is illustrated in the above graph. Acne treatments such as benzoyl peroxide or roaccutane cause the sebaceous glands to reduce their production of sebum. A common factor is the regular use of the wrong cleansers that strip the skin of its protective cover of sebum.

Soaps and other powerful cleansing agents strip the natural oils from the skin, as will a long hot bath. These oils (sebum) normally help lock moisture into the skin. When they are removed the skin rapidly loses moisture, resulting in the symptoms described in the introduction. If the skin is mistreated in this fashion over a long period of time it becomes weak. Effective treatment of the condition will be increasingly difficult.

Dehydration of the skin is the result of excessive water loss. A defective acid mantle, wind and sun, an artificially dry environment (heating and air conditioning) may cause rapid evaporation of moisture from the skin. The signs are similar to those of dry skin: the dreaded ‘dehydration lines’, a feeling of tightness, a lack of radiance of the skin, and a loss of elasticity. Worse still, dehydrated skin is a weakened barrier to external pathogens – the skin’s defences against outside influences are compromised. Scientific tests have proven that the skin pH can be increased significantly by alkaline cleansers. It can take up to 3 hours before the skin is able to re-establish a healthy pH level. Certain pathogens, in particular acne bacteria, thrive in an alkaline environment. A wrong cleansing routine can therefore increase the risk of acne.

Sterile skin is neither possible nor desirable. Products that interfere with the skin’s natural functions, or are designed to strip naturally occurring chemicals from the skin should be avoided. The first step in a good skin care routine should be a gentle cleanser that minimizes interference in the skin’s natural protective layer.

To find our more about caring for your skin follow the link