The skin is more than an expression of your health and youthful good looks. It is your one and only barrier between the internal and external realms, keeping in the good things and barring the bad. This complex organ is ingeniously designed, yet it faces new challenges in the modern world. It’s at risk of breaking down.
“Broken skin barriers” are real. They’re the subject of great interest from “skinfluencers” on TikTok, but they’re also studied rigorously by dermatologists. “We love the skin barrier but in a very physiologic and scientific way,” says Dr. Anthony Rossi, a dermatologist at Memorial Sloan Kettering Cancer Center.
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In addition to physically blocking the elements, the barrier employs its own micro police: immune cells and millions of healthy microbes that crack down on rogue skin pathogens, among other important jobs. In recent years, researchers have learned more about why the barrier fails, the consequences of a compromised barrier, and how to protect it for health and—yes—beauty.
The skin barrier is real
The skin barrier involves four layers of protection: physical, chemical, immune, and microbial. Rather than a pancake stack, think of these layers as links in a chain. “Everything is interconnected and interdependent,” says Dr. Richard Gallo, professor and chair of the department of dermatology at the University of California, San Diego. “If any link is weak, your chain breaks.”
The visible outermost part of the skin, called the epidermis, is responsible for most of the physical protection. It’s made of protein-rich cells plus fats, or lipids, that fill gaps between the cells. When this “brick and mortar” wall is robust, it holds natural moisturizing factors that keep the skin hydrated. It’s plump, crack-resistant, and shields harmful substances like UV rays and bacteria.
The fats in the epidermis play another role: supporting the chemical layer of protection. They do so by promoting an acidic environment that’s ideal for preserving the epidermis. This acidity also provides a comfy home for beneficial microbes while repelling pathogens.
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The third layer, immune, involves specialized cells that fight off skin infections before they spread. These immune cells are found in the epidermis and the layer beneath it, the dermis, which also houses nerves and blood vessels.
The fourth pillar of skin barrier defense is the skin microbiome. These microbes “produce all kinds of great stuff,” Gallo says, like molecules that kill pathogens and help build the fats needed for acidity and epidermal strength. Healthy microbes also outcompete pathogens for nutrients, adds Dr. Erin Chen, assistant professor of biology at MIT and a dermatologist at Massachusetts General Hospital.
If these protective layers fail, the skin breaks down, literally and figuratively. Tears or cuts can expose underlying tissue to harm. Skin conditions may develop such as atopic dermatitis and psoriasis. Life-threatening infections like MRSA and streptococcal bacteria could also gain a toe-hold. “They exploit the breaks in the skin,” Gallo explains.
Additionally, the risk of skin cancer goes up and wrinkles and skin blotchiness spread, along with acne. It’s not just looks; a compromised barrier may lead to systemic inflammation, which drives biological aging.
So, which intrusions chip away at the barrier’s defenses, and how can we thwart them?
Products that hurt the skin barrier
It turns out that we do much of the damage ourselves by applying skin products that harm the very flesh envelope we seek to protect. Like stunting a plant’s growth by over-watering it, overzealous self-care can undermine the skin barrier.
That’s especially true when using abrasive products. Chemical soaps and harsh cleansers have ingredients—such as foaming agents like sodium lauryl sulfate—that disrupt the fats in the epidermis, damaging and irritating the physical layer of protection. Cosmetics may have similar effects. “They dismantle the lipid membranes,” Rossi says. Soaps made from plant-based and other natural ingredients are often gentler on the skin than ones with sulfates and other synthetic additives.
Another issue is too much showering. Full-body soaping is rarely if ever needed, Rossi says. “The natural lather of washing with water is going to clean you off,” unless you’ve been sweating profusely, he explains. Dr. Bruce Robinson, a dermatologist in New York City, advises the regular use of soapy body wash for hairier parts only; soap more thoroughly just 1-2 times per week and limit showers to about five minutes.
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Steer clear of heavy exfoliants, says Dr. Esther Freeman, associate professor of dermatology at Harvard Medical School. These harsh products can change the acidity of your skin, impairing its microbial police powers against pathogens.
Many products have alcohols, dyes, and preservatives called parabens that can trigger allergic reactions and otherwise rub the barrier the wrong way. In particular, products with fragrances should be avoided. “We see so many skin allergies with fragrances,” Freeman says. “Especially if the barrier is not fully intact, you can induce an allergy over time.” Look for “fragrance-free” products. “Unscented” ones could still have chemicals masking fragrance, according to the EPA.
Since the pandemic, dermatologists have seen an overage of personal cleaning behavior, harming the skin barrier. Gallo notes one example: constant hand sanitizer, even without significant germ exposure. Just don’t underestimate the value of washing your hands, says Akiko Iwasaki, professor of immunology at Yale University. “Washing hands regularly with warm water and soap goes a long way in preventing infections,” she says. When handwashing isn’t possible, sanitizer becomes key, especially in germy environments. However, none of this requires a lot of showering, she adds.
Battling the elements: UV rays and pollution
Excessive self-care has ramifications beyond the confines of our bathrooms. Because it weakens the skin barrier, we’re more vulnerable to threats outdoors—most troublingly, UV rays from the sun.
Overcleaning strips away natural oils needed to produce a special protein called filaggrin in the epidermis. When plentiful, filaggrin keeps the barrier more hydrated and UV-resistant. With less filaggrin, more UV passes through.
By the same token, high UV exposure may cause filaggrin to degrade, as well as collagen and elastin, which boost the skin’s pliability and resilience, Rossi says, “and we know that it causes skin cancer.” By age 70, skin cancer strikes 1 in 5 Americans.
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Sunscreen is critical to prevent the barrier’s breakdown. Clothing matters, too, if you’re outside when the sun is strongest, from 10 a.m. to 4 p.m. “I’m a big fan of fabric with ultraviolet protective factor, which is like SPF for clothes,” Freeman says. A UPF rating of 30 or above is recommended.
Another threat to the barrier is environmental pollution such as particulate matter and hydrocarbons. “They wreak havoc on the skin by causing free radical oxidation,” Rossi says. “They definitely cause reactions in the skin that prematurely age it,” Robinson notes.
Preliminary evidence suggests that applying vitamin C topically before going outside could be protective. “It could potentially reduce some of the cytotoxic effects of particulate matter,” Freeman says.
Yet another issue is dry air, which “causes an inflammatory response and a whole cascade of problems,” Robinson says. “You begin itching, and the scratching causes physical trauma, which compromises the skin more, so it loses moisture.”
Moisturizer to the rescue
A good moisturizer can salvage the skin barrier. “We do things all of the time that make our skin function poorly,” Chen says. “So we have to put the water back in.”
Moisturizer battles the barrier’s enemies. Look for one with ingredients called humectants that attract and retain water from deeper layers of epidermis and dermis, keeping the outermost layer plump and strong. Robinson notes hyaluronic acid as an example; it holds up to 1,000 times its weight in water. Gallo recommends a close cousin, heparan sulfate, as potentially more effective. Glycerin is another beneficial humectant ingredient.
Rossi tells patients to dampen the skin before applying moisturizer. This “soak and smear” technique traps the water on the skin, which enhances the moisturizer’s effect, he says.
Other good moisturizing ingredients, known as occlusives, deliver fats to reinforce the gaps in the epidermis. “They act like cement or glue for our skin cells to stick together,” forming a unified front against assaults, says Rossi.
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Petroleum jelly, such as vaseline, is another kind of occlusive. It acts as a second shield over the skin barrier like a parapet protecting a castle, or as Freeman puts it, “a brick wall you’re putting on the skin.” The greasier the better, Chen says (but people with sensitive skin should avoid olive oil, which can be irritating).
Gallo sees a downside to occlusives. “They could block pores,” he says. “It’s worth considering, but shouldn’t be the only component to keep the barrier operating.”
Emollients like coconut or shea butter are a third moisturizer category. Experiment with products to find a personalized approach; a person’s needs depend on their genetics, among other factors. “What works well for one person might not work for others,” Gallo says. A dermatologist can provide guidance.
As with other products, moisturizers should be fragrance-free.
Go with your gut
Companies offer products for fixing a broken skin barrier. Few have been studied to determine their benefits. However, Robinson thinks some injectable medications handle the repair job capably. “They interrupt a cascade of inflammation in the skin,” he says, noting dupixent and JAK inhibitors as “gamechangers” for the right patients.
Some supplements provide probiotics marketed as improving the skin microbiome. These supplements “have not been shown to help the skin barrier,” Robinson says.
More generally, though, scientists are actively studying links between the gut microbiome and skin microbiome, called the gut-skin axis. Gallo found that when the skin barrier was damaged in mice, their gut microbiomes changed. “The organs talk to each other, and the microbiome responds,” he says.
This suggests that diets supporting a healthy gut microbiome could benefit the skin biome for a more effective barrier. Preliminary evidence shows that products made by gut microbes end up as building blocks for the skin. “The small molecules circulate through your blood to influence tissues throughout your body, including your skin,” Chen says.
Nutrition also promotes the development of building blocks for stem cells essential for the skin barrier to regenerate and repair itself. A healthy lifestyle overall slows down aging, which supports skin barrier longevity, Chen says.
Protect the barrier preventatively, before it breaks. “It’s more important than people probably realize,” Chen says. “Everyone should be thinking about their skin health.”