TEWL — or trans epidermal water loss — is a term you often hear in relation to skincare. But what does it actually mean?
Read on for your ultimate cheat sheet to all things TEWL, from how it impacts the skin barrier and hydration levels to what you can do to prevent it – and why you definitely should.
What is TEWL?
As the name trans epidermal water loss suggests (yes, it’s a mouthful), TEWL is the process of water leaving the body through the skin. The skin is made up of a number layers, with the epidermis being the uppermost layer closest to the surface. This is where water evaporates from. Our skin continuously releases water via TEWL, a process that is naturally regulated by the body.
Why is TEWL important?
As you may remember from school, humans are made up of 60% water. Water is a vital nutrient to the life of every cell and is responsible for many crucial functions within the body including regulating temperature, assisting in flushing waste and lubricating joints.
While TEWL is a naturally occurring process, too much water loss can cause issues for the skin and body as a whole. In general, low levels of TEWL equates to healthy, happy skin.
What causes TEWL?
Higher than normal levels of TEWL can be caused by a number of factors. Unsurprisingly, the environment plays a key role. For example, drying weather — both in cold and hot climates — will dry out your skin.
Products that strip or dry the skin can also cause issues. Think foaming cleansers with ingredients like SLS that upset the delicate balance of the skin and compromise the barrier. In fact, when the skin barrier is damaged in any way, TEWL increases; so if you’re suffering from a condition like eczema, chances are your levels of TEWL will be on the higher side.
You will normally notice if you have high transepidermal water loss thanks to a few telltale signs. Of course, dryness is the number one giveaway. Skin feeling tight, rough to touch or a little flaky? Blame the TEWL. More visible lines on the skin is also something to look out for.
How can you prevent and reduce TEWL?
Firstly, avoid any products that can sensitise or irritate the skin. Get to know the INCI list and steer clear of any ingredients known to aggravate sensitive skin. If in doubt, remember to always patch test a new product in a small area (say your neck or arm) before using it to avoid large scale reactions to the skin barrier.
Next up, it’s all about trying to keep the skin barrier as strong as possible. A healthy skin barrier means healthy skin and low levels of TEWL.
The best products for TEWL
The best tactic is to keep skincare simple, with skin-nourishing ingredients. Forget foaming cleansers that strip the skin, and instead use a gentle cream formula like Middlemist Seven, or an oil alternative like our Rosehip-powered Light Work. If you’ve been wearing make-up and SPF, you might want to do a double cleanse come evening where you use both.
Next up, a spritz of mist will help hydrate the skin and prepare it for the next round of products. Our recently reformulated Century Flower has been specifically designed to reinforce the skin's barrier function and reduce TEWL. We’ve added an anti-inflammatory Deep Sea Magnesium and Minerals complex, as well as prebiotic Inulin to fortify and protect the skin. It’s also enriched with Hyaluronic Acid to really hold moisture in.
Of course, you can also top up your hydration levels (and keep your skin barrier well supported) with a hardworking daily moisturiser. Love and Haight, our moisturiser for dry and dehydrated skin, is formulated with Avocado and Jojoba Oil to leave the skin hydrated, quenched and supple.
Last but by no means least, ceramide-based skincare is also a powerful way to bolster the barrier. Ceramides are found naturally in the skin and help to ‘glue’ our skin cells together, keeping them strong. Our Instant Kalm Ceramide Lightweight Face Serum and The Light Fantastic Ceramide Face Oil both contain a solid serving of a natural Ceramide Complex – apply after your mist to lock the good stuff in.