The misconceptions of dehydration and dryness | RATIONALE


Got the Winter Skin Blues?

Got the Winter Skin Blues?

Banish them completely by simultaneously boosting surface-level hydration and combating Trans-Epidermal Water Loss through the layers of the skin.

Recently, we’ve focused our education on the vital importance of pH levels and DNA repair processes within the skin and how they influence optimal skin health. So, as winter approaches and we all retreat into the comfort of our heated homes, we’re delving deeper into education of the epidermis and discussing hydration-supplementation strategies to reduce the risk of seasonal dehydration.

RATIONALE Immunologist Serum

RATIONALE's Immunologist Serum

A common misconception is that ‘dehydration’ and ‘dryness’ are interchangeable terms that describe the same conditions found in human skin. While they seem similar, these terms do differ:

  • Dehydration = a lack of water in the skin which requires hydration from water-soluble actives to both replenish and retain water. Dehydrated skin clogged by oil often remains dull, lacklustre in complexion and can feel uncomfortably tight.

  • Dryness = a lack of oil in the skin which requires moisturisation from oil-soluble actives to replenish and bolster its delicate lipid membrane. Dry skin that is hydrated but not sufficiently moisturised will still flake, irritate easily and present with a rough texture.

Dehydration and dryness are not always mutually exclusive. It’s possible (and quite common) for both to present at once, and for both conditions to be exacerbated by incorrect skincare. While hydration is what makes our skin soft, it won’t remain hydrated if there is no physical lipid barrier protecting that hydration from evaporating and escaping the skin. Similarly, to topically nourish skin that is suffering from dehydration may smooth the surface but it will still lack vital hydration necessary for supple volume and elasticity.

So, let’s talk skin salvation. The plan for combating dehydration and dryness is a two-fold approach.

Part one: Preventing Trans-Epidermal Water Loss

Trans-Epidermal Water Loss (TEWL) is the amount of water that passively evaporates through layers of the skin to the external environment, and is used to characterise barrier function. The average TEWL in human skin is approximately 300–400 ml per day, however, TEWL can be detrimentally accelerated by both genetic and epigenetic factors such as humidity, temperature (of either the weather or air conditioning – heating and cooling alike) and incorrect topical skincare actives that negatively work against the skin’s barrier rather than strengthening it.


Winter can particularly play a huge part in accelerated TEWL, as we tend to spend more time indoors with artificial heating and when we do go outside, our skin is shocked with drastic drops in temperature.


The solution: Skin Immunity + Hydration Supplementation

RATIONALE’s Immunologist range (Serum, UltraCreme, Mask) provides the skin with vital B-Group Vitamins acting as a booster shot for skin immunity and preventing TEWL while simultaneously regulating sebum production to a healthy rate, helping to retain hydration in the stratum corneum (skin’s outermost layers). 

RATIONALE ProCeramide Cleanser

RATIONALE's ProCeramide Cleanser.

Part two: Restoring the Protective Lipid Barrier Function

FYI, our skin’s sebaceous activity naturally declines as we age, resulting in an increase of xerosis (dry skin conditions) presenting in mature skin. However, younger skin is not invincible; TEWL poses a threat when damaging, astringent skincare formulations strip the skin of its natural lipid barrier (cleanser and exfoliants the prime culprits). This often wreaks havoc and causes the opposite effect—inducing breakouts, congestion and inflammation where sebaceous glands launch into overdrive in an effort to compensate for the lack of moisturisation. In fact, the skin’s barrier can actually take up to 72hrs to fully recuperate following this kind of damage.


The solution: Lipid Protection + Ceramide Production


RATIONALE’s ProCeramide range provides the skin with the vital lipids, including Vitamin E, Omega 3 + 6, Essential Fatty Acids and healthy Cholesterol, required to defend against daily environmental damage and work to encourage night-time repair. Ceramides are also an integral part of healthy skin-barrier function and encourage the skin’s own self-cleansing mechanisms. They are partly water-soluble and partly oil-soluble—and bond to dirt, makeup, sunscreen and organic debris found on the skin. When emulsified with water, they form cleansing micelles that remove this unwanted matter from the skin, leaving it smooth, soft and hydrated. With long-term use, this complete complement of skin identical Ceramides also encourages natural ceramide production in the skin.


Words by Sarah Noonan, RATIONALE Toorak Flagship Manager