What it is
Transepidermal water loss (TEWL) is the natural process of water evaporating from the skin into the air. It is a normal part of skin function, but when it is too high, it can lead to dryness, irritation and a weakened skin barrier.
Skin dehydration – High levels of water loss means the skin loses too much water, making it feel tight, rough or flaky.
Barrier damage – Excessive water loss can weaken the skin’s protective layer, leading to sensitivity and inflammation.
Premature ageing – A compromised barrier can make the skin more prone to fine lines and environmental damage.
How it works in skincare
Skincare products can strengthen the skin barrier and locking in moisture. Ingredients such as ceramides, glycerin, hyaluronic acid and fatty acids help trap water and repair the skin’s natural defences. Using moisturisers that contain both humectants (to attract water) and occlusives (to seal it in) is key.
High TEWL is common in conditions such as eczema, psoriasis and after overusing exfoliating acids or retinoids. If the barrier is damaged, harsh products can make it worse. Choosing gentle, barrier-supporting skincare is important when it is a concern.
