What Is The Skin Barrier?

Skin is the largest organ in the body, making up around one-seventh—or nearly 15 percent—of your total body weight. It is what separates your delicate insides from the harsh outside world, making it one of the most important organs in your body. Skin is composed of a vast, complex network of various cells, proteins, ceramides, and lipids—but arguably, the most vital component of all is the skin barrier.

If you’re a Kiehls fan, you’ve undoubtedly heard us talk about the skin barrier at some point—more than anything else, the skin barrier is what keeps your skin looking (and feeling) healthy. Keeping it nourished and hydrated so it can do its job well is essential for fresh, radiant-looking skin.

Ahead, we’ve put together a comprehensive guide to caring for this vital system. You’ll learn what the skin barrier is made of, how it works, and what you can do to keep it healthy and strong. Plus, we’ll provide recommendations on the best Kiehl’s products to use to keep your skin looking and feeling its very best. Read on for your comprehensive crash course on the skin barrier.

What Is The Skin Barrier?

In order to understand what the skin barrier does, you need to know how the skin is structured. You’ve probably heard that the skin is made up of three individual layers. That’s not entirely true—while there are three main layers of skin, each has several sublayers, most of which perform unique, specialized functions (skin is incredibly complex). For this article, however, we’ll be sticking to the three main layers: The topmost layer (epidermis), the middle layer (dermis), and the bottom layer (hypodermis).

The outermost part of the epidermis is the stratum corneum, or the skin barrier. Scientists often liken the stratum corneum’s structure to being like a brick wall. In this analogy, the skin cells are the bricks. Everything else—including the skin barrier—is the mortar that holds it all together. This mortar contains essential nutrients, like cholesterol, ceramides, and fatty acids. Together, these compounds are referred to as skin’s "natural moisturizing factor," because they help keep the deeper layers of skin hydrated and nourished.

What Does The Skin Barrier Do?

The skin barrier has several jobs, many of which are vital for your overall health. Of all of the skin barrier’s duties, researchers generally agree that it has three essential roles: Protecting your body from external stressors, like pollution and UV radiation, retaining water to keep your body and skin hydrated, and transporting vital nutrients to your skin.^I As a whole, these combined factors are responsible for maintaining homeostasis—in other words, keeping your body’s various systems balanced.

Your skin barrier is also the primary determinant of how healthy and even your skin looks. If it’s working properly, your skin barrier will retain water to keep your skin hydrated, smooth, and elastic. It’ll also fend off environmental aggressors, like pollution, and be less prone to sensitivity and irritation.

On the flip side, if your skin barrier isn’t working as it should, your skin will be vulnerable to damage. It’ll be more prone to dehydration, or trans-epidermal water loss, resulting in a dull, dry appearance. You’ll also be less able to fend off damaging aggressors, like free radicals, that can result in physical changes such as discoloration, laxity, and premature wrinkles. In fact, experts estimate that environmental influences are responsible for up to 97 percent of visible skin aging.^II In other words, any skin concerns you may have are almost certainly due, at least in part, to a poorly-functioning skin barrier.

What Causes Skin Barrier Dysfunction?

It would be nearly impossible to list every potential source of skin barrier impairment; everything from your genetic makeup to your lifestyle can affect your skin barrier’s health. The most significant factors that can impair barrier function are those you likely already know, like UV radiation, smoking, and chronic exposure to pollution. Physical damage—like that incurred from over-exfoliating—can also affect your skin barrier’s health, as can lifestyle factors, like your stress levels and how much sleep you get. Think of it this way: Any internal or external stressor that results in visible skin changes is likely capable of disrupting or damaging your skin barrier.

What Is The Skin Barrier?

What Does The Skin Barrier Do?

What Causes Skin Barrier Dysfunction?

How To Keep Your Skin Barrier Healthy: Your 6-Step Routine

Now that you know what the skin barrier is and how it works, we can get into the fun stuff: Specifically, skincare. While skincare alone won’t prevent barrier damage, the right routine can have a dramatic impact on your skin’s texture, resilience, and overall appearance. Read on for a complete six-step routine designed to keep your skin barrier strong and healthy.

Step 1: Cleanse To Remove Impurities

The first step in your healthy skin barrier routine is cleansing. Washing your face helps remove the dirt, oil, and pollutants that accumulate on your skin throughout the day and helps prevent them from damaging your skin barrier.

Start your routine off with our cult-classic Ultra Facial Cleanser. This Kiehl’s staple contains olive-derived squalane and emollient avocado oil to help cleanse your skin without stripping away any of its essential moisture. The ultra-gentle formula is pH-balanced and uniquely formulated to be suitable for all skin types, even sensitive skin. Dispense a dime-sized amount of this mild cleanser onto clean hands and massage it over your face in a circular motion. Then, rinse thoroughly with lukewarm water (super-hot water can dehydrate your skin—not a good way to start your routine).

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Step 2: Soothe Skin With Toner

Next, swipe on a gentle, alcohol-free toner, like Calendula Herbal-Extract Toner. This best-selling formula—a Kiehl’s favorite for nearly 60 years—helps remove any remaining dirt, oil, or cleanser residue without over-drying the skin. The soothing toner is infused with calendula petals to help refresh your skin after cleansing and prepare it for the remainder of your skincare routine.

To use it, soak a clean cotton pad in the toning liquid and swipe it over your face, taking care to avoid the eye area. Let the formula absorb into your skin for a moment before continuing on to your next step.

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Step 3: Apply a Strengthening Serum

After cleansing and toning your skin, reach for a concentrated serum, such as Vital Skin-Strengthening Hyaluronic Acid Super Serum. This concentrated formula stars 11kDa hyaluronic acid, an engineered form of hyaluronic acid capable of penetrating skin’s deeper layers. It also boasts a blend of skin-friendly adaptogenic herbs, including red ginseng root, which help protect against damaging environmental and internal stressors. The potent formula is clinically-demonstrated to double skin’s strength and increase resilience by more than a third. With regular use, it also helps improve the appearance of a slew of skin concerns, including fine lines and wrinkles, dullness, and uneven skin texture.* Apply the barrier-boosting formula to your face and neck after cleansing for more radiant, youthful-looking skin.

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Step 4: Reach For a Nourishing Face Oil

If your skin is dehydrated, it can’t perform its essential functions properly—which, as we described above, can result in the formation of countless skin concerns. Keeping your skin barrier well-hydrated, therefore, is essential for smooth, healthy-looking skin.

In the morning, apply two to three drops of the top-rated Daily Reviving Concentrate to your face and neck. This unique facial oil is formulated with a blend of antioxidant-rich plant oils, including sunflower oil, tamanu oil, and ginger root essential oil. It helps defend your skin against damaging environmental stressors while promoting a more energized, healthy-looking appearance. It’s non-comedogenic and suitable for all skin types, including oily and acne-prone skin.

At night, reach for a slightly richer oil, like Midnight Recovery Concentrate. This perennial Kiehl’s favorite contains olive-derived squalane, evening primrose oil, and fragrant lavender essential oil to replenish and nourish your skin while you sleep. In just one night, this unique formula helps refine skin texture and diminish the appearance of fine lines. With continued use, the moisturizing oil helps firm and smooth your skin for a visibly more radiant, youthful appearance. Like all of our face oils, this indulgent formula is non-comedogenic and suitable for all skin types.

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Step 5: Lock In Hydration

Face oil alone isn’t enough to keep your skin barrier well-hydrated. For proper hydration, moisturizer is vital. We recommend the cult-classic Ultra Facial Cream, Kiehl’s best-selling moisturizer. This top-rated face cream stars olive-derived squalane and glacial glycoprotein to nourish skin with lasting, 24-hour hydration. The unique formula is clinically-demonstrated to smooth and soften dry skin without a heavy or greasy feel.** It’s suitable for all skin types and absorbs into the skin easily to leave skin hydrated and visibly healthier with regular use.

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Step 6: Protect Your Skin With SPF

Last but not least is the most important step in keeping your skin both physically healthy and healthy-looking: Sunscreen. We know you’re well aware of the importance of sunscreen, but we’ll reiterate anyway. In addition to protecting your skin against painful sunburns, sunscreen is instrumental in helping to reduce your risk of skin cancer. It’s also one of the most effective weapons in your anti-aging skincare arsenal, as studies show approximately 80 percent of skin aging results from UV radiation.^II

For lasting protection, apply a broad-spectrum sunscreen as the final step in your skincare routine every day (yep, even in the winter). We recommend Super Fluid Daily UV Defense 50+, which offers both UVA and UVB protection. The lightweight formula also contains antioxidants, including vitamin E, which help protect against other environmental stressors, like airborne pollution. This best-selling formula is non-comedogenic and suitable for all skin types, though those with sensitive skin may prefer a mineral formula, like Super Fluid Daily UV Mineral Defense, instead. Whichever you choose, be sure to apply your sunscreen generously, and follow other sun protection guidelines like avoiding direct sunlight between the hours of 10 am and 2 pm.

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*Based on a four-week clinical study of 58 subjects tested in urban and polluted environments. Based on the Skin Strength Index, a composite average score of skin suppleness, plumpness, and resiliency.
**Results based on a four-week clinical test.

Next: Understanding Different Types Of Skin Discoloration

^I.Rosso, James Del et al. "Understanding the Epidermal Barrier in Healthy and Compromised Skin: Clinically Relevant Information for the Dermatology Practitioner: Proceedings of an Expert Panel Roundtable Meeting." The Journal of clinical and aesthetic dermatology vol. 9,4 Suppl 1 (2016): S2-S8.
^II.Zhang, Shoubing, and Enkui Duan. "Fighting against Skin Aging: The Way from Bench to Bedside." Cell transplantation vol. 27,5 (2018): 729-738. doi:10.1177/0963689717725755