What Is Transepidermal Water Loss (TEWL)?

transepidermal water loss

Proper hydration is crucial for healthy skin. As the name suggests, transepidermal water loss (TEWL) refers to the evaporation of water through the epidermis, or outer layer, of your skin. (TEWL is pronounced “TOOL” )  When TEWL is high, your skin becomes dry, itchy, and often irritated. People with atopic dermatitis (eczema), contact dermatitis, psoriasis, and other similar conditions have weakened skin barriers, which allows for greater TEWL than normal.

The good news is that transepidermal loss can be reversed and prevented with the right skin care regimen based on your Baumann Skin Type®. This article provides an overview of what TEWL is, why it happens, and what you can do to prevent it and restore healthy, happy skin.

What Is TEWL and What Causes It?

Transepidermal water loss occurs when the skin’s protective barrier is damaged or impaired, allowing excess moisture content evaporate from the skin into the atmosphere. The result is dry, dehydrated, and/or irritated skin.

To understand what causes TEWL, we need to first understand the layers of your skin. The epidermis is the top layer of skin, which is comprised of four to five sublayers. Beneath that is the dermis, which is primarily made up of collage, hyaluronic acid, heparan sulfate, other glycosaminoglycans and elastin. The hypodermis is beneath the dermis and is mostly used for fat storage to keep you warm.

The topmost layer of the epidermis is called the stratum corneum (SC). The structure of the SC is arranged similarly to a brick wall made up of 15 to 30 layers of cells (the bricks), with intercellular lipids (the mortar) in between. The function of this “brick and mortar” layer of skin is to prevent TEWL, as well as prevent irritants and allergens from entering. When the skin lacks adequate lipids to create this protective barrier, TEWL can occur.

Not only does a damaged skin barrier allow for increased transepidermal water loss, but it also allows pathogens to enter the skin, which can cause a whole host of unwanted conditions.

Two different instruments can measure transepidermal water loss to determine if you have a weakened skin barrier. One is called a TEWAmeter and one is an Evaporimeter.

How to Repair the Skin Barrier and Prevent TEWL

The right combination of topical moisturizing ingredients can work to repair a damaged or weakened skin barrier and therefore reduce transepidermal water loss. One of the most effective barrier repair ingredients is a lab-created substance called myristoyl/palmitoyl oxostearamide/arachamide mea, or MLE technology.

MLE technology mimics the lamellar structure of your skin’s natural lipids and therefore can strengthen its barrier and reduce TEWL.

The ideal moisturizing regimen for barrier repair will include several different types of moisturizing ingredients, including humectants, occlusives, and emollients.

  • Humectants work by drawing in moisture from their surrounding environment. While humectant ingredients can hydrate your skin by pulling in water from the air, they can also dehydrate your skin by drawing moisture out of the deeper layers of skin when the air is dry.
  • Occlusives seal in moisture to your skin and prevent irritants and pathogens from getting inside. Occlusives are often combined with humectants to increase skin hydration.
  • Emollients make the surface of your skin smoother and softer.

The exact ingredients and products that will be best for your skin are determined by your Baumann Skin Type®. Zerafite™ MLE formulations can be a very effective choice for dry or sensitive skin types. Zerafite Barrier Repair Moisturizer, Zerafite Soothing and Calming Moisturizer, and Zerafite Ultra Rich Body Cream use MLE technology to replenish your skin’s lipid content and improve its barrier function. These products can only be purchased through a physician, so work with a Skin Type Solutions physician to determine your Baumann Skin Type® and see if these moisturizers could be right for you.  (If you can’t get to a physician- you can use my doctor’s code which is DRB)

Bottom Line

Dry, dehydrated skin is a common problem for women and men alike, especially if you live in an area where cooler, drier air is starting to move in for the winter. Work with an STS physician to create a customized skin care plan that will take into account your Baumann Skin Type® and skin barrier function. For more information, contact our Miami office.

Be sure to follow Baumann Cosmetic on Facebook, Instagram, and YouTube for more skin care tips, recommendations, and how-to videos from Dr. Baumann and her team of experts.

Wishing you great skin!


©2018 MetaBeauty, Inc.

December 20, 2018 Eczema/Dry Skin