Transepidermal water loss sounds like a problem that should be dealt with by the EPA, or NASA, or the up-and-coming physicist or biochemist.

OK, so you were really close with the biochemist guess. Transepidermal water loss (TEWL) has everything to do with you and your skin!

What is Transepidermal Water Loss?

When you break the terms down, it’s not as complicated as it sounds:

Trans: across

Epidermal: The outermost layer of your skin

Water Loss: Do we need to explain that one?

So, in simplicity, TEWL is the loss of water from your skin. When water passes from the dermis through the epidermis and evaporates from the skin’s surface, this is known as transepidermal water loss.

This is actually pretty important to you when considering skin dryness or hydration. Although it’s often overlooked, TEWL is one of the main reasons why moisturizing the skin regularly and using the right products is crucial in keeping skin healthy and hydrated.

How Does Transepidermal Water Loss Work?

Your skin is made up of three layers:

Epidermis is the outermost layer.

Dermis is the middle layer.

Hypodermis is the innermost or under-most layer.

When water leaves the dermis, passes through the epidermis, and then evaporates, it’s lost forever: TEWL.

The epidermis is sort of like the protecting armor. It’s known as the skin barrier, preventing pollutants and diseases from invading our body. Its job also involves keeping water and moisture inside the layers of skin.

Each day, the skin loses approximately one pint of water through TEWL. When the air is pretty humid, water evaporation from your skin is slow, and the body is able to quickly replenish what it loses to the air. But when water evaporates faster than the body can replace it, the skin becomes dehydrated, which can lead to irritated, rough and/or itchy skin that can crack and cause discomfort. Your skin may feel tight or parched like the Sahara Desert.

Dry, dehydrated skin appears to be more aged, as fine lines and wrinkles are accentuated. As the skin begins to show signs of dryness, TEWL accelerates even further because the skin’s barrier function is further limited. When the skin barrier is compromised, it leaves it vulnerable to infection, disease, and free radical damage.

What Can Affect Transepidermal Water Loss?

Your skin typically naturally regulates TEWL pretty well on its own, but when your skin’s barrier function is damaged, TEWL can be affected. Conditions like sunburn and eczema can wreak havoc on the epidermal layer. Internal factors like metabolism and sweat gland activity can have an impact, too. Low humidity and topically-applied products that dry the skin out can increase TEWL.

There are two concepts that need to be understood when considering TEWL:

Hydration addresses the water content of your skin.

Moisturization measures the skin’s ability to hold on to water molecules.

In order to keep TEWL in check, both need to be addressed by your chosen skin care products.

How To Prevent Too Much TEWL

Taking good care of your skin is vital to its health. You know that drinking plenty of water will help to keep your skin hydrated from the inside, but you still need to address the issue of keeping that moisture in.

A good-quality moisturizer will address the concern of TEWL. You should opt for a moisturizer that includes both humectant and occlusive ingredients.

Humectants like hyaluronic acid draw in moisture from the air (or from within the body) and pull it to the epidermis.

Occlusive ingredients create a seal over the skin to prevent water loss.

When working together, they help to create a reservoir of moisture in the epidermis and act as a barrier on the skin to help prevent TEWL by sealing in that moisture. The bonus is that occlusive agents also help to keep pollutants, toxins, and harmful bacteria out.

MDSUN’s luxurious Super Intensive Moisturizer works to give your skin a more firm, radiant and youthful complexion. It’s perfect for mature or dry skin to rekindle your skin’s best condition. It’s also ideal for oily and younger skin to defend and prevent future aging. It infuses your skin with high-grade caviar for a restorative effect. Hyaluronic acid draws moisture to the epidermal layer, while allantoin seals it in, creating younger-looking skin with a brighter undertone and soft texture.

Since TEWL is faster when the skin’s barrier function is interrupted, the amount of water that comes into contact with the skin should be limited, as water dilutes and washes away skin oils that act as natural occlusives. Heavy soaps and cleansers will quickly diminish the natural oils, too. Opt for gentle cleansers or glycerin bars.

Very hot water will also increase TEWL. In dry climates, or during dry seasons, plug a humidifier into your home or office.