When customers message Nicolas Travis, the founder of the skin-care brand Allies of Skin, with questions about their sensitive skin, he asks them what other products they’re using. Ninety-nine percent of the time, he said, it’s something with drying alcohol or harsh essential oils.

“I have to tell them, ‘You’ve just spent years of using really badly formulated products, which is like years and years of eating junk food,’” said Travis, whose company is based in Singapore and is in stores in 15 countries, including the United States. “I say, ‘Your skin isn’t sensitive, your skin barrier is just really weak.’”

Ask aestheticians and dermatologists what problem they’re seeing these days, and as often as not the answer is a broken-down skin barrier. Little wonder, then, that the new beauty buzzwords are “barrier repair” (and its cousin “barrier protection”).

A broken barrier — symptoms include inflammation and patchy, flaky skin — can eventually lead to other problems since it means the skin’s defenses are compromised. Besides sensitive skin, barrier dysfunction is also partly responsible for rosacea, eczema, psoriasis and acne, all of which are on the rise, according to epidemiological studies.

What’s to blame for the mass barrier malfunction? Too many creams, serums and other hopes in a jar.

“It’s largely a product of our own obsession with squeaky clean and using product upon product upon product,” said Whitney Bowe, a dermatologist in New York. Combine product overload with environmental assaults, and you have a recipe for skin barrier disaster.


Here’s how to avoid that — or to repair the damage.

What’s the acid mantle, and why you absolutely must protect it

The acid mantle is the protective film of natural oils, amino acids and sweat that covers your skin. Damage it with too much scrubbing or neutralize it with alkaline washes and you’re on your way to barrier problems: inflammation, allergies, breakouts.

Talk of the acid mantle (apologies!) means a lot of talk about pH, which, to the surprise of many a chemistry teacher, is the sort of thing beauty addicts love to discuss online these days. So, while alkaline water may be all the rage for health, you definitely don’t want to use it on your (acidic) face.

Cleansing your skin with anything alkaline interferes with the skin’s ability to repair itself and makes it less elastic, Bowe said. A high pH also encourages the growth of a bacteria called propionibacterium acnes that, as you may guess from the name, plays a major role in many forms of acne. That face wash that is super-foamy and lathery? There’s a fairly good chance it’s alkaline because the ingredients that give it those qualities are high pH.

“The problem is, people want lather to feel clean,” said Emily Parr, a founder of HoliFrog, a line of cleansers that is set to debut in September. “So we had to counter ours with a ton of rich oils to reinforce the barrier.” (The brand’s namesake frog is a nod to its focus on barrier protection; frogs’ skin is so permeable that they can’t survive in toxic environments.)

Christian Surber, a professor of dermatopharmacology at the universities of Basel and Zurich and an author of studies on the acid mantle, suggests avoiding products with a pH of more than 7. This doesn’t mean the lower the pH the better; skin pH is about 5.5 and ability to tolerate more acid depends on both your skin and how well the product is formulated.


Skin grows more alkaline as we age — activating enzymes that chew away, Pac-Man-like, at collagen — and acidic products can restore pH, protecting against droopy skin and the development of wrinkles.

This focus on acidity as the key to healthy skin is the theory behind such startups as Atolla, in the Brooklyn Navy Yard, which tests for factors including pH and sends monthly customized serums. It’s also why companies like Travis’ and Parr’s list pH on the packaging (something Surber, who is not connected with either, thinks all brands should do).

The phrase “pH balanced” is about as useful as the term “clean” or “natural” — which is to say, it means nothing. If you want a specific number, the company has to supply it. Not even a cosmetic chemist (or armchair cosmetic chemist) can guesstimate this based on ingredients, Surber said.

The bad news: When researchers tested 31 moisturizers widely available in the United States, they ranged in pH from 3.73 to a havoc-wreaking 8.19. A 2018 German study found only a little over a third of commonly available moisturizers had a pH “appropriate for barrier protective basic therapy.” (Companies constantly tweak formulations, so it’s impossible to have a complete updated list of villains.)

Dos and don’ts of restoring your skin barrier

The first step in skin barrier protection is stepping away from the kajillion products.

“The 10-step Korean regimen is an ordeal for the skin,” Surber said.


Chemical exfoliants like glycolic, lactic and salicylic acid are usually more gentle than physical exfoliants (particles in scrubs, microdermabrasion) but should be used no more than once a week for dry or sensitive skin and three times a week for oily skin. Consider a recent meme that made its way around beauty insiders: “Look, I can totally fix your acid mantle, if you could just lay off the 30% glycolic for 10 minutes.”

Initially there was a lot of excitement among doctors about ceramides, which glue the barrier back together and help prevent the skin from drying out and wrinkling. But the skin is simply too complex for any single ingredient to do the job, said S. Tyler Hollmig, an assistant professor of dermatologic surgery at Stanford University. He still recommends ceramides, but they’re not a cure-all.

Products with ingredients like glycerin, petrolatum and hyaluronic acid can also help repair the skin barrier and replenish lost moisture. These don’t need to be fancy. Shari Marchbein, a dermatologist in New York, advises that, as basic as it sounds, moisturizer should be applied within 60 seconds of cleansing to trap in the hydration.

“If you frost a dry cake, the cake is still dry,” Marchbein said. “If you frost a moist cake, it stays moist.”