The skin is the largest organ in the human body, with an important role to play in thermoregulation, keeping out harmful organisms and maintaining a barrier between the internal body and the outside environment.

When the skin is dry it’s ability to do this is compromised.
Some of us are predisposed to a ‘dry‘ skin type i.e. those with eczema, certain genetic skin conditions and some chronic systemic diseases like diabetes and renal disease.

However, ‘Dry skin’ will affect us all to some extent as we age and with changes in external factors like the weather!
In winter the air is colder, drier and the use of air conditioning further exacerbates the ‘dryness’ of the air. Dry air sucks up more water from our skin particularly if the skin barrier is compromised.

Is there a difference between dry and dehydrated skin?
A dry skin is lacking in ‘lipid content’ resulting in a deficient skin barrier. The integrity of the skin barrier is maintained by lipids like ceramides, fatty acids and cholesterol as well as natural moisturizing factors (NMF). In addition, sebaceous glands produce sebum which forms a protective seal over the surface of the skin. A problem with any one of these systems can lead to dry skin.

Dehydrated means reduced ‘water content’ and this occurs when a damaged skin barrier allows water to escape from the skin. We call this transepidermal water loss or TEWL. Dehydration needs to be treated by retaining water in the skin and preventing further loss.

We can conclude from this that a dry skin, with poor barrier function, will certainly lead to dehydration.

Clinically dry and dehydrated skin may look and feel like the same thing. Most commonly affected areas are the shins, flanks, back and exposed areas of the face and neck. The skin has a rough, flaky or scaly feel and is itchy or sensitive. When left untreated the skin can become inflamed, weeping and possibly infected. Dry skin on the face can give one a dull complexion and make the skin look wrinkled and aged.

The best scenario would be to try to avoid the problem entirely by moisturising the skin.
Moisturise! Moisturise! Moisturise! is a mantra Dermatologists preach to eczema sufferers or anyone that is predisposed to dry skin. Moisturisers as a whole are the most commonly prescribed products by dermatologists. Certainly we should all adopt this habit in winter.

Moisturisers work by repairing and supporting the function of the skin barrier in retaining water in the skin and preventing water loss. They don’t add water to the skin.

Traditionally there are 3 different types of moisturisers.
Humectants work by drawing water to the stratum corneum (outer-most layer of the skin). They are hygroscopic molecules. Examples of these are glycerin, alpha hydroxyacids and urea.

Occlusives work by creating a barrier on the surface of the skin so water can’t evaporate. Examples are lanolin, petrolatum, dimethicone, silicone and zinc oxide.

Emollients contain molecules that fill up the gaps in the stratum corneum. Emollients give skin a soft, supple feel. Examples are squalene, fatty acids, cholesterol, and hyaluronic acid.

In reality,moisturisers have evolved to have a combination of ingredients that perform more that one function. New age moisturisers contain natural moisturising factors (NMF) like glucosamine, and peptides and other novel ingredients.
The fact that the cause for dryness varies among individuals, accounts for why certain moisturisers work better in some rather than others. Finding the perfect moisturiser for your skin is sometimes a matter of trial and error. A dermatologist or therapist can advise you.
Also as the state of our skin changes, we should be aware of the need to change our moisturiser appropriately as needed.

This is of course why we have such a huge variety!