You are mostly water. From head to toe, every layer of your skin and every single cell in your body depends on it to function. Water nourishes, revitalizes, and keeps you glowing. So what happens when your skin starts to lose it, and why does it matter?
Our expert Albert Navasa, ISDIN Corporate Medical Affairs Specialist, has the answers. Today, he’s explaining everything you need to know about transepidermal water loss (TEWL), how it impacts your skin, and why a hydration boost might be the key to healthier, happier skin.
Table of Contents
What is transepidermal water loss?
While it might sound technical, TEWL is simply a natural process where water evaporates from the surface of your skin. It’s also a key indicator of how well your skin barrier is working. Your body is about 60% water, and nearly a third of that is in your skin — your body’s largest organ. Every day, a bit of that water is lost through TEWL.
Albert explains: “This process refers to the amount of water that evaporates from the top layer of the skin, known as the stratum corneum.” The stratum corneum — your skin’s outermost layer — acts like a shield, keeping moisture in and protecting you from external stressors.

Why does TEWL happen?
Your skin is always interacting with the air around you, and that air has different humidity levels depending on where you are. To balance things out, water on your skin’s surface evaporates. As Albert says, “TEWL is completely natural and unavoidable.”
The idea is to keep this process in check because some factors can speed it up, leaving your skin dry and dehydrated. Albert shares what can cause excessive water loss:
- Environmental conditions: Low humidity, air conditioning, or extreme temperatures can pull moisture from your skin.
- A weakened skin barrier: Overexposure to the sun, irritation, or harsh products can damage the skin barrier, causing more water to escape. “An increase in TEWL may signal an unhealthy skin barrier,” Albert explains.
- Genetics: Everyone’s skin is unique. Some people are naturally more prone to water loss.
- Aging: As the years go by, your skin becomes thinner and less effective at holding moisture.
- Stress and skin conditions: Inflammatory skin issues like psoriasis or eczema can weaken the barrier further and increase moisture loss. “Variations in TEWL can also indicate underlying problems with the skin barrier,” Albert notes.
“TEWL is a helpful indicator of your skin barrier’s health. And keeping your barrier balanced is key to maintaining hydration.”
The solution? Daily, consistent hydration that works for your skin type and needs. Speaking of skin types, let’s see how TEWL varies depending on yours.
How does your skin type affect TEWL?
Your skin type plays a big role in how much water it loses. Albert breaks it down for us:

Normal to dry skin: People with normal skin typically have a balanced skin barrier, meaning TEWL tends to be moderate and stable.
Meanwhile, dry skin often lacks the natural oils and moisture needed to keep the barrier strong. This makes it easier for water to evaporate, increasing TEWL.
Oily or combination skin: Oily skin produces more sebum, which strengthens the skin barrier. This helps hold in moisture and keeps TEWL on the lower side.


Sensitive skin: The science is still up in the air on this group — while some sensitive skin studies cite slightly more TEWL, others report an average amount.
Is your TEWL level healthy?
So, how can you tell if your TEWL level is where it should be? Albert shares a simple rule of thumb, “If your skin feels soft, smooth, and hydrated — and there’s no flakiness or irritation — that’s a good sign.”
“If your skin feels soft, smooth, and hydrated — and there’s no flakiness or irritation — that’s a good sign.”
On the other hand, if your skin feels rough, dry, or irritated, it could be losing more water than it should. The good news? There’s plenty you can do to get it back on track.
Expert tip: Although our experts have reviewed this article, your dermatologist knows your skin best. Head in for a visit if you feel like something’s off.
How to give your skin deep, lasting hydration

Imagine giving your skin a long drink of water — and then locking it in. Albert says that’s the secret, “To fight transepidermal water loss, you need to hydrate your skin and then seal that moisture in.”
Here’s how to create a simple, effective routine to keep your skin happy and hydrated:
- Cleanse: Start with a gentle facial cleanser to clear away impurities without stripping your skin.
- Hydrate: Apply a hydrating eye cream and serum with hyaluronic acid. Hyaluronic acid is a hydration hero that also helps boost elasticity.
- Moisturize: Finish with your go-to moisturizer to seal in all that hydration and keep your barrier strong.
- Sunscreen: Protect your skin daily with broad spectrum sunscreen to help prevent sun damage, which can dry out your skin and worsen TEWL.
- Exfoliate: Consider adding an exfoliant with glycolic acid to your routine a few nights a week to remove dead skin cells. This may help hydrating products absorb into skin more effectively.
Embrace your skin’s natural rhythm

Forget perfection. Your skin changes every day, and that’s okay. Some days it needs extra hydration, and some days it feels its best on its own. The important thing is to care for it consistently.
By making hydration a daily habit, you’re giving your skin exactly what it needs to thrive. After all, healthy skin isn’t about perfection — it’s about balance, care, and loving the skin you’re in.
References:
- Green M, Kashetsky N, Feschuk A, Maibach HI. Transepidermal water loss (TEWL): Environment and pollution-A systematic review. Skin Health Dis. 2022 Feb 25;2(2):e104.
- Akdeniz M, Gabriel S, Lichterfeld-Kottner A, Blume-Peytavi U, Kottner J. Transepidermal water loss in healthy adults: a systematic review and meta-analysis update. Br J Dermatol. 2018 Nov;179(5):1049-1055.
Behind the blog:
Article written and reviewed by:
Our namesake embodies the spirit of embracing life and all its wonder. As wellness journalists, we explore topics that invigorate the senses and keep curiosity alive. We believe that glowing skin is the result of a healthy body and mind. Weaving beauty with science, we aim to inspire you to live young at every age.