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Transepidermal Water Loss: What it is + How to Prevent It

Whether we’ve just landed in a new city or are feeling the after-effects of a late night out with friends, chances are you’ve experienced the discomfort of dry, tight skin. These symptoms of dehydrated skin are also signs that your skin’s naturally-occurring transepidermal water loss (TEWL) has gone out of whack.

So how do you fix it? Skincare scientist Kendall Johnson, our Head of Product Development, explains.

What is Transepidermal Water Loss

“Transepidermal water loss — or TEWL —  is an inevitable physiological response that occurs when water passively evaporates through the skin into the air,” says Kendall. “TEWL is happening to everyone throughout the entire day, although the process accelerates dramatically at night.” This is why you often first experience the telltale dry, tight sensation of accelerated TEWL in the morning just after you wake up.

Causes of Accelerated Transepidermal Water Loss

As Kendall explained, TEWL is part of skin’s natural function. TEWL-related dehydration therefore only occurs when the process accelerates. This can occur for a number of reasons, including:

  • Living in or traveling to a low-humidity climate
  • Aggressive skincare practices such as over cleansing or using too many harsh ingredients
  • Exposure to UV rays

“By far the most water loss occurs while we sleep,” says Kendall.  “This is linked directly to our body temperature decreasing and skin temperature rising with the skin pH decreasing.”

In addition, most people sleep in low-humidity environments due to heating or air conditioning, both of  which dehumidify the air and draw moisture away from the skin’s surface.

How TEWL Affects the Skin

“Signs of skin dehydration and dryness may appear when the rate of water loss is faster than the skin's ability to hydrate,” explains Kendall.

Signs may include:

  • Flakiness
  • Rough patches
  • Increased visibility of fine lines
  • A tight, uncomfortable feeling

How to Balance TEWL

“Because transepidermal water loss accelerates overnight, it’s best to build a nighttime skincare routine rich in humectants that bind to water such as hyaluronic acid, glycerin, and ectoin,” says Kendall. “Ceramides, niacinamide, probiotics, and occlusives which lock in moisture are also great ingredients to incorporate.”

A Protective Nighttime Skincare Routine

The best way to keep TEWL in balance is to prevent it from accelerating to a point that you experience symptoms of dry skin. Follow this nighttime routine to keep skin hydrated and nourished so you awaken moisturized and glowing:


Start by applying an oil-based cleanser such as our Antioxidant Cleansing Oil to a dry face. This light and silky cleansing oil effortlessly dissolves impurities and makeup while adding a burst of squalane-fueled hydration. Meanwhile, nourishing antioxidants target stress and signs of aging, leaving the skin healthy, radiant, and nourished.


Balance your skin with a refreshing spritz of Hyaluronic Acid Facial Mist  to plump and prep skin for the rest of your routine. This award-winning formula is made with two types of hyaluronic acid to weightlessly restore hydration inside and out for complete, skin-plumping moisture protection and all-day radiance.


The skin around your eye area is thinner than elsewhere on your face, making it more delicate and sensitive. Deeply hydrate and moisturize with our multi-award-winning Marine Algae Eye Cream. Paracress extract instantly lifts and firms while pink marine algae, a natural source of peptides, plumps fine lines and wrinkles. Our superhero hydrator, squalane, seals in hydration with  deep and lasting protective moisture.


Massage a dropper full of our luxurious, silky Copper Peptide Rapid Plumping Serum into your face as the third step in your skincare routine to instantly plump fine lines and wrinkles. In this bestselling serum, hyaluronic acid and ectoin  join forces with copper peptides to draw in moisture and flood skin with continuous hydration while encouraging collagen production to boost elasticity and add bounce.


Top your treatment with our  Omega Repair Cream to deeply nourish and repair the skin’s protective barrier.  Our award-winning moisturizer uses ceramides and omega fatty acids to deliver lasting hydration and strengthen the skin’s natural moisture barrier, visibly improving fine lines and wrinkles while helping prevent overnight moisture loss.


Topping your moisturizer with a non-comedogenic facial oil locks in moisture to further slow TEWL’s overnight acceleration.

Our 100% Squalane Oil goes one step further by driving skincare actives 40x deeper into the epidermis, making your skincare work harder as it weightlessly locks in moisture and delivers deep hydration. Our sugarcane-derived squalane is a molecular match for the moisture naturally found in human skin. It’s also pregnancy-safe and fragrance-free, making it safe for every skin type.

Christine Tusher
Christine Tusher Writer and expert
As a lifestyle writer and journalist, I love sharing my passion for ocean conservation and obsession with clean beauty. I’ve tried almost every trend and ingredient, and Biossance’s science-backed formulas are the only ones that consistently calm my reactive skin and make it smoother, clearer, and healthier. I’m so excited to be on this journey of skincare innovation with Biossance, and to share it with you!

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