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Article Overview
- Trans-epidermal water loss (T.E.W.L.) refers to the evaporation of moisture from the skin, which can lead to dehydration and skin barrier weakness.
- Factors such as age, environmental aggressors, and skincare habits can contribute to T.E.W.L.
- To minimize T.E.W.L. and maintain skin hydration, it is important to incorporate humectant and occlusive ingredients into your skincare regimen.
- Humectants attract moisture to the skin, while occlusives act as a barrier to minimize T.E.W.L. and protect against environmental aggressors.
- Ingredients like hyaluronic acid, glycerin, urea, and vitamin B5 are effective humectants, while fatty acids and vegetable-derived oils are beneficial occlusives.
What is Transepidermal Water Loss?
Transepidermal water loss (TEWL) refers to the process of water passively evaporating from the skin to the environment. TEWL as a concept is mainly used in scientific testing and research settings to assess the skin moisture barrier and the skin's overall condition.
TEWL happens to everyone, with the average TEWL being about 300-400mL a day (Honari & Maibach, Applied Dermatotoxicology, 2014). Depending on the skin’s condition and certain environmental factors, this may be lower or higher. In this article we’ll break down TEWL in more detail, what causes it and how to minimise its effects.
How transepidermal water loss affects the skin
The skin has three main layers; the outermost layer known as the epidermis, the middle layer (or dermis), and the deepest layer, known as the hypodermis. Transepidermal water loss occurs when water travels from the dermis to the epidermis and evaporates from the skin’s surface.
Research has shown that higher transepidermal water loss may indicate the skin’s moisture barrier is weak. Conversely, lower transepidermal water loss may be associated with a stronger skin moisture barrier. The strength of the moisture barrier can impact your skin’s condition and its appearance.
What are the signs of high levels of transepidermal water loss?
When you have an increased TEWL you'll notice signs of skin dehydration and dryness. If the rate of water loss from the epidermis is much faster than the skin's ability to rehydrate, you may notice your skin feels dry, rough or have visible flaking. You might also notice more pronounced fine lines.
What causes transepidermal water loss?
Transepidermal water loss is a natural process, but skincare habits, your skin type and certain environmental factors can impact the skin moisture barrier's function and increase TEWL.
Age
Transepidermal water loss can be affected by age and vary depending on the area of the body. As we age, the skin cell renewal cycle slows down and collagen production declines, we're more likely to have increased TEWL.
Skin type
Dry skin types that have underactive sebaceous glands might take longer to rehydrate the skin after water loss, so they may have a higher risk of TEWL. Sensitive skin is also more prone to having their skin moisture barrier function being impaired which can exacerbate transepidermal water loss.
Environmental factors
Since TEWL is linked to the moisture barrier function, certain environmental factors can play a role. Low humidity, pollution, and sun exposure can impact the skin's moisture barrier function which can increase transepidermal water loss.
Skincare habits
Skincare habits such as over-exfoliation, under-moisturising, or using harsh skincare ingredients can disrupt the skin moisture barrier and contribute to trans-epidermal water loss.
How to prevent transepidermal water loss
Some water loss in the skin can be unavoidable, but lifestyle changes and the right skincare can help to reduce the effects of TEWL and maintain skin hydration.
- Stay hydrated: Drinking plenty of water helps to keep the whole body, including the skin, hydrated.
- Protect from the sun: Because prolonged sun exposure affects the skin moisture barrier, sun protection, including a broad-spectrum sunscreen, is vital to minimising transepidermal water loss.
- Use gentle skincare: Look for gentle, hydrating skincare products to support the skin moisture barrier
- Avoid over-cleansing: Over-cleansing or using exfoliants too frequently can strip the moisture barrier, leaving the skin more susceptible to TEWL.
- Moisturise night and day Moisturiser is essential to attracting and locking in hydration which is key to minimising TEWL. Aim to moisturise right after showering or onto damp skin as this will help the skin absorb the product better.
How can skincare reduce transepidermal water loss?
Hydrating skincare can have a dramatic impact on the effects of TEWL on the skin. To keep the skin hydrated, it’s important to incorporate humectant and occlusive ingredients into your skincare regimen.
- Humectants help attract moisture to the epidermis to keep the skin hydrated, either from the air if there’s enough humidity or from lower layers of the skin. Humectant ingredients to look for include hyaluronic acid, glycerin, urea, and vitamin B5.
- Occlusive ingredients create a barrier over the skin to trap moisture, making them great for dehydrated skin. Occlusives include lanolin, mineral oils, olive and soybean oils, and beeswax.
When combined, the two ingredients play a key role in minimising transepidermal water loss, while also protecting against environmental aggressors and irritants.
SkinCeuticals solutions for TEWL
Some products do contain both humectants and occlusives, but given occlusives tend to be thicker in consistency, they are oftentimes found in different formulas. Depending on your skin type you might opt for a lightweight, hyaluronic acid product for your daytime routine and use an occlusive moisturiser at night.
It’s good to also note that occlusives can exacerbate oily or blemish-prone skin, so these skin types should always opt for the more lightweight humectant formulas to prevent excess oil buildup. Here’s our recommendations for hydrating skincare to manage transepidermal water loss.
Hydrating B5 Gel
Featuring moisture-attracting hyaluronic acid and vitamin B5 to promote barrier repair, this oil-free serum can be added to any skincare regimen for extra hydration or used as a stand-alone moisturiser for oily or blemish-prone skin.
SkinCeuticals Phyto Corrective Range
Phyto Corrective Gel, Phyto A+ Brightening Treatment, and Phyto Corrective Mask all provide skin affected by TEWL with the hydration it needs along with a soothing blend of botanical ingredients.
Triple Lipid Restore 2:4:2 Anti Ageing Moisturiser
In addition to its powerful anti-aging benefits, this advanced moisturiser is formulated with ceramides, natural cholesterol, and fatty acids to keep the skin hydrated. The nourishing formula also improves the appearance of skin smoothness, laxity, pores, and overall radiance.
Epidermal Repair Soothing Cream
Ideal for replenishing moisture and restoring the skin moisture barrier, this cream soothes the skin and reduces visible redness. Its deeply nourishing formula helps to lock in moisture to help prevent transepidermal water loss.
Shop Featured Products
Hydrating B5 Serum
A hydrating, hyaluronic acid serum that replenishes moisture and restores radiance for a smoother complexion. The oil-free formula also contains vitamin B5 for acne-prone skin.
Phyto Corrective Hydrating Mask
Intensive soothing botanical hydrating facial mask for sensitive skin.
Triple Lipid Restore 242 Anti-Ageing Moisturiser
Ceramide Face Cream with Lipids to Nourish & Hydrate Dry Skin
Epidermal Repair Soothing Cream
Face cream for sensitive skin. Repair cream designed to support compromised skin moisture barrier.
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