Transepidermal water loss is a phrase you’ve probably heard dermatologists and experts talk about, but what exactly is it?
It’s no secret that there’s a constant stream of new information, confusing phrases and impressive-sounding ingredients within the skincare vernacular. From our obsession with retinoids, to exfoliating enzymes and even milia, every day could well be skincare school day if you wanted it to be.
One particular term that you might have heard dermatologists and skincare experts talk about is transepidermal water loss (often shortened to TEWL). Sounds a bit complicated, we know, but it’s actually something that’s worth being aware of.
But what exactly is TEWL? “We all have a skin barrier which requires a careful balance to maintain healthy skin. Part of this balance is maintaining water within the skin,” says Dr Emma Craythorne, SkinCeuticals’ consultant dermatologist. ”If your barrier is compromised in some way you will start to lose this water – this is transepidermal water loss.”
“In healthy skin, TEWL is always proportional to skin hydration. The problems start when the ratio of TEWL is inverted, skin hydration is decreased and TEWL increased,” explains Dr Tiina Meder, GetHarley dermatologist and founder of Meder Beauty. “Extremely cold or extremely hot air will increase TEWL, as will smoking, air pollution or ultraviolet radiation. Another important trigger is stress; the key stress hormone, cortisol, influences the skin lipids production, hyaluronic acid balance and many other processes which lead to skin barrier damage and therefore increases TEWL.”
The key symptom to be aware of is skin that feels dry, tight or irritated. “They’re all signs the skin barrier is compromised and it could be an ongoing issue or something you’re suddenly experiencing,” adds Dr Craythorne.
Although it might sound overwhelming, the key to preventing TEWL is actually fairly simple. “Dryness and dehydration can be improved with regular moisturisation,” says consultant dermatologist Dr Sharon Wong. “Using a good quality emollient with additional humectants means you can trap more moisture onto the skin.”
It’s also worth noting that skin actually loses the most water at night time. “That’s why I always recommend using a hyaluronic acid serum just before bed that can work as an additional moisture boost,” says Dr Wong. Other ingredients to look out for include ceramides, emollients and humectants, like glycerin and colloidal oatmeal.
The best products to prevent transepidermal water loss
Aveeno Calm & Restore Triple Oat Serum
Brand new to the UK, Aveeno’s serum is formulated with colloidal oat, oat oil and oat extract for the most soothing of triple threats. Apply it before moisturiser to smooth skin and strengthen the skin’s barrier.
Dr.Jart+ Ceramidin Cream
Consider this our new obsession: a five-ceramide complex supports, protects and hydrates skin while simultaneously soothing and restoring a depleted skin barrier.
Niod Multi-Molecular Hyaluronic Complex
Formulated with no fewer than 15 forms of hyaluronic acid, this serum penetrates deep into skin to ensure it’s hydrated on every level. A true powerhouse.
SkinCeuticals Triple Lipid Restore
This moisturiser contains a blend of ceramides, natural cholesterol and fatty acids to hydrate skin as well as improving its overall texture.
Murad Intense Recovery Cream
Packed with shea butter and macadamia oil, this comforting cream protects skin against environmental aggressors while locking in hydration.
Meder Hydra-Fill Deep Hydration Mask
Loaded with hyaluronic acid to instantly hydrate skin, these masks are also formulated with vitamin E to protect skin cells and carrageenan, an ingredient extracted from natural algae that forms a hydrating barrier on the skin’s surface.
Images: courtesy of brands