All About Transepidermal Water Loss (TEWL) and Skin Hydration
IN THIS ARTICLE:
- What is TEWL?
- What is the importance of TEWL?
- How can you prevent TEWL?
- Tips to minimize TEWL
- Final words
If you’re a skincare lover like me, then you probably know that proper hydration is one of the key factors to healthy, happy skin.
Truly, there are so many advantages to hydrated skin. Some of these include improved elasticity, reduced appearance of fine lines and wrinkles, improved skin protection and balanced sebum production. In other words, when you’re working to keep your skin hydrated, you’re also building the foundation to good skin days, every day!
Now, if you’ve been reading our blog posts, you may have noticed a term that keeps popping up here and there: Transepidermal Water Loss (TEWL).
While the beauty industry is swamped with super complex, smart-sounding terms (case in point, the entirety of our “How Our Skin Works” article), most of them are just fads. However, TEWL is a fundamental part of our human biology, and the term probably won’t go away any time soon. In fact, the more you learn about skin anatomy, the more you’ll realize why TEWL is such an important concept to understand.
So, what exactly is TEWL? And why do you need to pay attention to it?
What is TEWL?
TEWL is the natural process that our skin uses to regulate its water content. And it’s something that happens to all of us.
Officially speaking, “TEWL is the amount of water that passively evaporates through the skin to the external environment."(1) TEWL is directly proportional to skin hydration, with the average rate in healthy skin being about 300–400 mL/day,(1) up to 500mL/day.(2)
However, different people might experience TEWL differently. For example, the TEWL of a person with naturally dry skin will be higher compared to someone with oily skin. In addition, the TEWL rate can change for many reasons, including the environment and skin disorders.
If you’re in an environment with high humidity levels, TEWL will decrease. On the other hand, if you have an impaired skin barrier, perhaps due to excessive exfoliation, eczema or psoriasis, your skin will have a hard time holding onto water, and the amount of TEWL will increase.(1)
What is the importance of TEWL?
“Okay Graydon, that’s cool and all, but I still don’t see why we have to make such a big deal out of it.”
Well, my friend, that’s exactly what I’m going to talk about right now!
As I’ve mentioned, TEWL is directly correlated to the level of skin hydration, making it a widely used method to determine the health of your skin barrier function.
Simply speaking, if your TEWL is low, your skin is doing a pretty good job of holding onto water and that means your skin is hydrated and healthy. And vice versa, if your TEWL is high, your skin is having trouble retaining water, for one reason or another, and probably feels dry, cracked, flaky and even irritated.
However, it goes a bit deeper than that.
By measuring TEWL, a skin professional can also find out whether or not you have a skin barrier dysfunction, such as atopic dermatitis (AKA: eczema). In this case, TEWL is a sensitive indicator of skin irritation. It can also be used to analyze the irritancy potential or protective properties of topical products.(1) Basically, by measuring TEWL, we can also understand whether or not a skincare ingredient can help our skin retain hydration better.
TEWL can be measured through different methods in a medical setting, such as a dermatologist’s office. There are many instruments that the dermatologist can use, including an open chamber, unventilated chamber or condenser-chamber device. However, as mentioned, TEWL can easily be influenced by the surrounding environmental factors, such as humidity, temperature and airflow. Therefore, these tests need to be done under controlled conditions.(3)
How can you prevent TEWL?
Since too much TEWL means that your skin will become dry, flaky, dull and irritated, our goal should be to stop it from happening, right?
Well, not exactly.
TEWL is a completely natural process that serves a function, and just like with everything else, balance is key.
If there’s absolutely no water loss from the skin, then we run into the issue of over-hydration, which is also known as skin maceration. This is the process where our skin breaks down when there’s an excess of water. Think about when you spend too much time relaxing in the bath—your skin becomes all wrinkly and soft, right? Well, something similar could happen if there’s no TEWL.
Therefore, the goal isn’t to completely stop TEWL. Rather, the goal is to prevent excessive moisture loss.
Tips to minimize TEWL
- Choose a good cleanser
Have you ever used a cleanser, only to feel super dry and tight afterwards?
Well, that could mean you’ve just stripped your face of its hydration and natural oils and your skin barrier has become impaired. Over time, if this keeps occurring, your skin might develop more irritation issues. Therefore, you need to choose a cleanser that not only does a good job of removing impurities, but is also gentle on the skin.
At Graydon Skincare, we’ve formulated two cleansers, Aloe Milk Cleanser and Face Foam, that can both help you cleanse properly AND respect your skin barrier. You can even use both of them in the same routine as a double cleanse.
- Moisturize properly
Okay, so if there’s too much TEWL, then you just have to reinforce your skin with hydration by using moisturizers, right?
I promise there’s a bit more nuance to this.
First, let’s talk about an ideal moisturizer. In my experience, a well-formulated moisturizer includes three kinds of moisturizing ingredients: humectants, emollients and occlusives.
A humectant is basically a magnet for water; it works by pulling water from the environment into your skin. An emollient helps to keep your skin soft and supple. And an occlusive acts like a protective layer; it helps to seal moisture into your skin.
We have a range of moisturizers, including Berry Rich, Phyto Clear, Putty and Skin Stuff all of which are formulated with different kinds of moisturizing ingredients and offer something for every skin type.
Now, let’s talk about when and how to apply your moisturizers.
Aside from the obvious post-cleanse, the best time to apply moisturizers is right after showering. This is important because water actually evaporates off the skin faster after a shower, leaving it dehydrated. You see, after showering, there’s a higher concentration of moisture in your skin compared to the air. And since water moves from areas of higher concentration to those of lower concentration (thanks science), your skin will lose hydration even quicker once you step out of the shower.
If you cleanse your face in the shower, that results in even more water loss. Cleansers are formulated with surfactants, which help to remove sebum and other impurities; however, they can also disrupt the bilayer lipids, making it more difficult for your skin to hold onto water.
So, as soon as you get out of the shower, start your post-cleanse skincare routine before doing anything else.
- Use an occlusive
In addition to your regular moisturizer (which may include some occlusive ingredients), you can take it a step further by adding in an occlusive, like a face oil or a balm. My preference is face oil, and here’s why.
While it’s true that our skin naturally produces oils, face oils can bring things to the next level by complementing your natural oils. Aside from being an extra layer of protection for your skin, face oils can also have many skin benefits if they’re formulated properly.
Our Superfood Serum is a revitalizing face oil, formulated with superfood ingredients like raspberry seed oil, goji seed oil, oat oil, saffron extract, turmeric and more. These ingredients work together to nourish your skin and protect it from environmental stressors.
So if your skin is on the drier side, don’t hesitate to add a face oil like Superfood Serum into your skincare arsenal.
- Be mindful of active ingredients
Active ingredients are wonderful. Depending on the specific skin concerns you have, you can use different actives to address them, bringing you closer to your skin goals.
However, it’s easy to overuse active ingredients and that’s when problems can begin. While some people might be able to tolerate lots of actives, this isn’t true for everyone. Overusing or misusing ingredients like retinoids or exfoliating acids can damage the skin over time. And once your skin barrier is damaged, TEWL is worsened.
So always listen to your skin and use your active ingredients wisely.
So there you have it!
Transepidermal Water Loss (TEWL) is a totally normal process in which our skin releases its water content into the air. While it happens to everyone, we should try to minimize it because dehydration can lead to dull, irritated skin that’s also prone to fine lines and wrinkles.
Good thing is, there are many common practices that we can do to keep TEWL in check. And if you follow the tips I’ve presented above, then you should be in a pretty good position to keep your skin hydrated and happy.
And that’s it.
Wishing you good skin days, every day!
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Main image by: evgenyatamanenko
(1) Honari, Golara, and Howard Maibach. Applied Dermatotoxicology: Clinical Aspects. Academic Press, 2014. ScienceDirect, https://www.sciencedirect.com/science/article/pii/B9780124201309000013.
(2) Jansen van Rensburg, S, Franken, A, Lodewykus Du Plessis, J. Measurement of transepidermal water loss, stratum corneum hydration and skin surface pH in occupational settings: A review. Skin Res Technol. 2019; 25: 595– 605. https://doi.org/10.1111/srt.12711
(3) Alexander, Helen et al. “Research Techniques Made Simple: Transepidermal Water Loss Measurement as a Research Tool.” The Journal of investigative dermatology vol. 138,11 (2018): 2295-2300.e1. doi:10.1016/j.jid.2018.09.001