Understanding Eczema: The underlying factors behind your dry, itchy skin

Sofia Bowers
Sofia Bowers
September 20, 2023 · 5 min read Sources Verified

You’ve probably heard eczema often described as a chronic skin condition characterized by inflammation, itching, and dryness. But that definition doesn’t really explain the underlying reasons for those symptoms.

Growing up with eczema, I felt so frustrated with my skin because I lacked an understanding of how my skin responded. All I knew was that my flare ups were associated with things like pet allergies, sweat, and stress. I just wanted to know what was so different about my skin that gave me an uncontrollable itch whenever I pet my cat.

Over time, I've discovered personal methods to manage eczema symptoms. While these methods provide relief, they don't address the fundamental cause of my eczema.

What Causes Eczema?

Understanding how normal skin functions is essential to unraveling why eczema-prone skin reacts to various triggers and allergies. Learning what distincts eczema-prone skin from normal skin can help you learn to support and care for your skin better.

Normal Skin: A Strong Barrier

Did you know that your skin has a turnover rate of 28 days?

It’s like a fortress that’s renewed, brick by brick (or cell by cell), monthly. Your skin acts like a barricade to prevent invaders like allergens and harmful bacteria from intruding and wreaking havoc.

Skin Barrier
Skin is the first barrier of defense against allergens and bad bacteria.

Good bacteria and tiny proteins called AntiMicrobial Peptides (AMPs) are like soldiers that guard your skin by targeting the bad bacteria. AMP’s also help recruit your immune cells to fight these invaders.

Good Bacteria fight Bad Bacteria
Antimicrobial peptides and good bacteria strengthen your skin barrier defense against bad bacteria.

Skin is also supposed to be good at keeping water in. Like a sponge; the more water it holds, the better it is at its job. A way to measure this is with something called Transepidermal Water Loss (TEWL). Lower TEWL rates correlate with stronger skin barriers. So the less water skin loses, the stronger it’s supposed to be.

Your skin has a barrier protein called filaggrin (FLG) that acts like a superhero, locking arms with other proteins to create a barrier against allergens and bad bacteria, while protecting and keeping water inside your skin.

Eczema Skin: What Makes it Dry and Itchy?

How Genetics Can Make you Predisposed to Eczema

Predisposed to Eczema, Filaggrin Deficiency, Genetic Mutation

People with eczema often have some genetic quirks that can cause skin composition to be different that leads to dryness, itch, and inflammation. A lot of people with eczema have a mutation for the FLG gene, a well known predisposing factor for eczema. This mutation can decrease the amount of this skin protein. The FLG mutation can be influenced by an overactive immune system, resulting in reduced FLG levels and increased sensitivity to allergens and irritants. A 2018 article by authors Kim and Leung describes this in detail if you would like to learn more.

Eczema Causes in Children vs. Adults

Have you ever wondered why some children grow out of eczema and others still have eczema as adults? Well, one study found this could be because kids that grow out of eczema only inherited the FLG skin protein mutation from one parent, while those who have eczema into adulthood have the mutation from both parents.

Eczema Genetic Predisposition, Filaggrin Mutation

Eczema and Skin Inflammation

Eczema skin also produces fewer AMPs, proteins that act like tiny soldiers that fight off bad bacteria. That's why we're more prone to infections, which makes our itch symptoms even worse.

When the balance of skin bacteria is off, the skin's immune response goes haywire, leading to more inflammation and worse eczema. It's like a vicious cycle.

Eczema skin also struggles with something called tight junctions (TJs), the structures that form seals between skin cells. Curent research has shown that TJ’s ability to keep water in and keep bad bacteria and allergens out is dependent on skin inflammation, independent of FLG. This also contributes to the vicious cycle, because the more impaired those seals are, the more inflamed your skin is and vice versa.

differences between normal skin and eczema skin, filaggrin deficiency
Differences between normal skin and eczema skin (filaggrin deficiency)

The skin's surface layer, known as the lipid matrix, is made of cholesterol, free fatty acids, and ceramides (a specific type of fat molecule). Imagine free fatty acids as the mortar that cements the walls of your skin, sealing the gaps of your surface skin cells. In eczema-prone skin, the lipid matrix has also been found to be compromised because of lower ceramide levels and altered ceramides. The fatty acids and ceramides of eczema skin have also been found to be shorter in length. This can allow things we don’t want like bad bacteria and allergens to creep in and contribute to a weak skin barrier.

Eczema and Dry Skin

The combination of compromised gaps between skin cells, skin proteins, and fats, can not only allow more things to sneak in, but more to escape out. This can make eczema prone skin susceptible to water loss. People with eczema often have higher TEWL (TransEpidermal Water Loss) rates, meaning more skin water loss than the average person. This could be a reason why eczema skin often feels so dry.

If you’ve ever noticed like me that your skin thrives in very humid climates, this is not your imagination. There is some scientific backing to this. TEWL decreases with increasing humidity. FLG (the skin protein mentioned earlier) breaks down in low humidity. However, a humid environment will actually prevent this breakdown. Because FLG helps keep water in your skin, not enough FLG leads to water evaporating out of your skin. If your eczema does a lot better in higher humidity like mine, this could be a reason why.

Sweat: An Eczema Trigger and Helper

What Does Sweat Do? Functions of Sweat

Sweating can make eczema act up, but it’s also essential to our skin health. It helps with regulating body temperature and skin moisturization. Sweat also helps us fight off bad bacteria.

People with eczema often face sweat-related challenges because of differences in the skin barrier. There are actually two forms of sweat dysfunction in people with eczema: not sweating enough and sweat leakage.

People with eczema are thought to actually not sweat enough. Normally when someone is experiencing stress or anxiety, sweating increases. A study found that the opposite happened for people with eczema. Another reason people with eczema might not sweat enough could be because of blocked skin pores. The sweat of people with eczema has also been found to contain less of the ingredients that help with fighting bad bacteria and moisturizing skin. So this combination of sweating less and lack of skin moisturizing and bacteria fighting components could lead to drier and more irritated skin after sweating.

Sweat Leak Inflammation
When sweat, filled with salt, bad bacteria, and allergens leaks in, can increase inflammation.

Having impaired TJ’s (the seals between skin cells) can let sweat leak back into the skin. This can create opportunity for pesky bacteria, irritants, and salt from the skin surface to leak back in and cause trouble. Sweat in sweat glands has also been found to leak into the tissues around sweat glands in people with eczema, which could also result in more irritation and inflammation.

Science-Based Treatments: Treating the Underlying Contributors to Eczema

The good news is that scientists are using all this knowledge to develop treatments that target the root causes of eczema. Moisturizers with certain ingredients like petrolatum, AMPs, and probiotics might help. There's also something called Targeted Microbiome Therapy.

By understanding what's happening beneath the surface, we're getting closer to finding practical solutions for managing eczema.


So, there you have it, the science behind eczema, and what does it reveal? Eczema skin is structurally very different from normal skin! From genetic predispositions to the intricate workings of your skin's barrier, we've uncovered some of the underlying factors behind eczema skin’s tendencies to dryness, itch, and bacterial infection. This understanding can shed light on valuable insights for those of us who are seeking to manage and soothe eczema symptoms.

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