What is Transepidermal Water Loss, and How Is It Linked to Eczema?

Did you know that the average person loses 300 - 400 mL of water through their skin each day? This happens during a normal process called transepidermal water loss (or TEWL for short). It’s not the same as sweating, but rather a passive process of water vapour evaporating into the air through the skin.

In people with eczema, the skin barrier is compromised and may not function properly to keep TEWL in check. If the body loses too much moisture through the skin, it can lead to dehydration and dry, tight, itchy and uncomfortable skin. These symptoms can keep the unpleasant eczema itch-scratch cycle going, which is why it’s so important to nourish and protect the skin barrier to prevent excessive TEWL.

What can cause increased transepidermal water loss (TEWL)?

We all experience TEWL to some degree, but certain factors can speed up the process and cause us to lose too much water through our skin. These may include: 

• The environment. Humidity levels and pollution can both affect TEWL. For example, in lower humidity conditions, the dry air is more likely to pull moisture from the skin and increase TEWL. In higher humidity, TEWL may decrease. Chronic exposure to air pollution (1) can also cause oxidative stress that damages the skin barrier, which may increase TEWL.
  

• Skincare habits. Using harsh cleansers that strip the skin, over-exfoliating, or using products with too many active ingredients can damage the skin barrier and increase TEWL. When it comes to skincare for our little ones, opt for gentle products that are designed for sensitive baby skin!
  

• Inflammatory skin conditions like eczema. Those with conditions like eczema have impaired skin barrier function, which can result in higher water loss through the skin. Higher TEWL can be caused by eczema, but it can also contribute to worse eczema symptoms - so breaking the cycle is crucial.

How can I reduce transepidermal water loss for my eczema-prone child?

Transepidermal water loss is a normal bodily function, so we shouldn’t aim to eliminate it altogether. Instead, we want to do what we can to restore or maintain a healthy skin barrier so it can better regulate TEWL and keep it within a normal range. Higher TEWL can exacerbate eczema symptoms and leave their skin more vulnerable to external invaders and irritants.

Itchy Baby Co. skincare is designed especially for babies and children with itchy, dry and sensitive skin, to help nourish and support a healthy skin barrier. And here’s how we do it:

• Our Natural Shampoo & Body Wash is a gentle, sulphate-free and fragrance-free wash that cleanses the skin without over-drying. It also contains native emu-apple extract, known for its antioxidant properties to help protect against free radicals.
  

• Our Natural Oatmeal Bath Soak is made with 100% colloidal oatmeal, an ingredient that acts as a humectant to help draw moisture from the air into the skin. Colloidal oatmeal also helps soothe itching and relieve symptoms of mild eczema. By controlling these symptoms, we can help reduce the chance of further damage to the skin barrier (and the associated increase in TEWL).
  

• Our waterless Eczema Moisturiser contains nourishing occlusive ingredients like coconut oil, beeswax and shea butter that help to create a physical barrier on the skin to seal in moisture and help reduce TEWL. For best results, we recommend using it immediately after bathing with our Oatmeal Bath Soak to lock in as much goodness as possible. Gently towel dry the skin and apply the moisturiser while the skin is still damp - usually within two minutes of drying off. And most importantly, keep it consistent! You should moisturise their skin at least once or twice per day.

By nourishing and protecting your little one’s precious skin barrier, you can help to regulate TEWL and maintain happier, healthier skin.

This blog post was brought to you and your family with love from the Itchy Baby Co. team x.

Disclaimer: Information provided is of a general nature only, and you should always consult your medical professional.

Sources: 

(1) Green, M., Kashetsky, N., Feschuk, A., & Maibach, H. I. (2022). Transepidermal water loss (TEWL): Environment and pollution-A systematic review. Skin health and disease, 2(2), e104. https://doi.org/10.1002/ski2.104