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What is the skin barrier and why does it matter? Here’s what you need to know

From the Experts | Sep 01, 2023
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What is the skin barrier? You might have heard dermatologists talk about how vital it is, but even the biggest skincare connoisseurs may be unsure of what this so-called barrier looks like. Is it a sunscreen? A face mask? A new type of serum? The answer is much more straightforward than that. The skin barrier is, quite simply, the outermost layer of your skin.

And, at last, it’s getting the attention it deserves, with beauty editors praising barrier-bolstering routines in order to keep this protective layer strong. More and more are realising that a healthy skin barrier is the true answer to a calm complexion. So, let’s explore everything you need to know about your skin barrier, from the way it’s structured to its key functions…


What are the 3 main layers of the skin?

First, let’s look at where the skin barrier sits in the overall structure of your skin...

  • The outer layer is the skin barrier. Also known as the epidermis, it is what you most commonly think of as ‘skin’ because it’s the protective part that you can see.

  • The middle layer is the dermis. This is where you’ll find complexion-plumping collagen, elastin, nerve endings and the skin’s blood supply. It also cushions your body from stress and strain, while the skin barrier keeps it protected.

  • The bottom layer is the subcutaneous layer. The subcutaneous tissue here not only provides insulation, but it also attaches the other skin layers to tissues under the skin, like bones and muscles.


The skin barrier unveiled

Because the skin barrier (or epidermis) is the very top layer of your skin, its purpose is to protect not just the lower layers of skin, but your body as a whole. It’s shielding you from external aggressors, such as pollutant particles and UV rays, and it also locks in nourishment to keep your complexion balanced and soothed.

This one layer of skin has a unique structure of its very own, with three key cells supporting its function as a full-body shield. These include…

  • Langerhans cells, which control your skin’s immune response to bacteria, fungi and viruses.

  • Keratinocytes, which are like the ‘bricks’ of healthy skin, held together by ceramides, oils and cholesterol to create a strong and supportive wall.

  • Melanocytes, which produce melanin, the substance that gives skin its pigmentation. These cells also absorb UV rays to protect the lower layers of skin from sun damage.


So, why is the skin barrier so important?

As we said before, the most crucial role of the skin barrier is protection. It shields your body from external aggressors, such as pollutants, pathogens and UV radiation. But as well as keeping harmful toxins out, it also locks nourishment in to prevent water loss, so you can maintain optimal hydration levels in your skin and your body as a whole.

In short: the skin barrier controls the entry and exit of substances through the skin, a little like your body’s very own, built-in security system. However, the skin barrier can become compromised if it’s not given the care and support it deserves, which is why it’s important to learn (and steer away from) any causes of skin barrier damage.

Some of these causes include:

  • Environmental factors, such as polluted air and UV radiation.
  • Over-exfoliation from using too-harsh scrubs too often.
  • Harsh chemicals found in astringent skincare products, such as toners.
  • Unhealthy habits, including lack of sleep, a low-nutrient diet and not drinking enough water.
  • Hormonal changes and ageing.

What is the skin barrier’s function?

1. Full-body protection

The skin barrier is exactly as it sounds; a barrier that shields your body from UV radiation, pollutant particles and other external aggressors. It’s your first line of defence against any toxins that come your way, so it’s important to support it with skincare products for skin barrier repair.The skin barrier is exactly as it sounds; a barrier that shields your body from UV radiation, pollutant particles and other external aggressors. It’s your first line of defence against any toxins that come your way, so it’s important to support it with skincare products for skin barrier repair.

2. Maintenance of nutrients

As well as keeping the ‘bad stuff’ out, your skin barrier locks the ‘good stuff’ in. It seals in all the nutrients that keep your skin and body healthy and hydrated. If you’re dealing with dry, itchy skin, it may be that your skin barrier has become compromised, meaning it’s not able to lock down the moisture you need for a smooth, supple complexion.

3. All-weather shield

The skin barrier adapts to the seasons to safeguard your body from the pore-damaging effects of harsh weather. For example, when brisk, cold winds threaten to strip delicate pores, the barrier works hard to keep moisture in (although it can break down without help from hydrating face creams). Meanwhile, the melanocyte cells that make up the skin barrier help to absorb UV rays to defend the lower layers – a function that’s best supported with a broad-spectrum SPF.

4. Immune defence

The langerhans cells in the skin barrier are there to support your immune system. They identify and attack pathogens (including bacteria, fungi and viruses) to prevent infections in your body.

5. Sensory perception

There are sensory receptors in the skin barrier that allow you to sense touch and temperature. They do this by sending signals to the nervous system that tell you, for example, if you’re cold or feeling pressure.

So, the skin barrier’s functions go far (far) beyond maintaining your complexion; it plays a huge role in the overall health and wellbeing of your body as you move through daily life.

Signs of a damaged skin barrier

Do you suspect your skin barrier might be damaged? Here are just some of the signs to watch out for:

  • Dryness and dehydration, often caused by gaps in the skin barrier which allow moisture and nutrients to escape.

  • Itchy skin and eczema, which may be as a result of dehydration or bacteria that’s infiltrated the barrier.

  • Chronic skin irritations or infections, also caused by a weakened barrier that’s not able to fully protect the skin against pathogens.

  • Rosacea and redness, two symptoms of a skin barrier that is stressed and suffering from inflammation.

  • Delayed wound healing because the skin isn’t able to repair itself as quickly or effectively as usual.

  • Hyperpigmentation from overexposure to UV rays, which you’re more likely to notice if you haven’t applied SPF as frequently as needed.

The good news is your complexion will heal over time. Skin naturally renews itself, so fresh, healthy cells can appear and restore your radiant glow. Just make sure you’re avoiding the causes of damage and take the correct steps to repair your skin barrier.

Other things to know about your skin barrier

How does the skin act as a protective barrier?

The outer layer of your skin – the epidermis – acts as a barrier that covers your whole body, protecting the cells, tissue, muscle, bones and organs that lie beneath. It’s your first line of defence against harmful substances, from pollutants to viruses, so it plays a vital role in shielding you and fending off toxins. This isn’t just good for your skin; it benefits your wellbeing as a whole, which is why bolstering your skin barrier is about more than unlocking a radiant glow.

What is a damaged skin barrier?

Think of the skin barrier as a protective wall. When it becomes damaged or imbalanced, gaps can form in the barrier which allow toxins to get in and nutrients to get out. This can be caused by anything from harsh, cold weather to UV damage, to wear and tear from a too-harsh skincare routine. That’s why your skin barrier needs support to keep it strong and healthy in the face of aggressors.

What happens when your skin barrier is damaged?

A compromised skin barrier is more likely to let irritants, allergens and infections in, leaving your complexion prone to dryness, dehydration, itching and redness. So if you notice that your skin looks inflamed, stressed out or simply feels off balance, this could be a sign that the barrier is damaged and needs deep repair.

What can cause a weak skin barrier?

If you have naturally sensitive skin and/or suffer from chronic skin conditions like eczema, you may find your skin barrier becomes damaged more easily. However, a weak skin barrier can also be caused by daily habits, such as getting too little sleep, not drinking enough water, smoking or eating a diet that’s low in nutrients.

The environment comes into play too, with polluted air, extreme weather and UV radiation all putting additional stress on your skin barrier. Meanwhile, using harsh skincare products, such as pore-stripping toners, will affect your skin’s pH balance, leaving your complexion vulnerable. That’s why it’s so important to follow a gentle and balanced skincare routine; one that not only heals damage but prevents it from happening in the first place.