If you grew up in the 2000s, you're probably familiar with a few beauty clichés. The woman splashing her face with water in the face wash commercial, the mascara that comes off in a perfect "C" on a makeup wipe, and two mysterious little words in the voiceover: "moisture barrier." For as long as we can remember, beauty brands have promised products that "restore the moisture barrier" or "prevent damage to the moisture barrier." That all sounds good. We know we want skin to be moisturized, and I've always pictured my more nourishing products as little knights of hyaluronic acid on horseback surrounding the moat that is my skin, which threatens to pour out at any time if this barrier doesn't hold. But that's a metaphor, and dermatology is a science, so I asked doctors to explain what the moisture barrier really is.
What Is the Moisture Barrier?
"The skin's moisture barrier does exactly what it sounds like — it helps the skin to retain moisture, specifically water," says New York-based dermatologist Kenneth Mark. Simple, right?
Los Angeles-based dermatologist Anna Guanche gets specific: "The skin barrier consists of the epidermis and, most specifically, the hard, outermost layer of the stratum corneum." The epidermis is what we typically think of as the outer layer of the skin, but it's made up of five layers. The outermost layer of the epidermis is the stratum corneum.
"The stratum corneum is a layer of actively shedding dead skin cells," says Guanche. "It's fortified with a latticework of remaining cell-to-cell connections and the contents of your oil glands that contain lipids."
Why Is It Important?
Put simply, the barrier works to keep good stuff in and bad stuff out. Essential water and electrolytes are sealed in, explains Guanche, which keeps skin looking smooth and dewy. At the same time, it protects the skin from dehydration and repels irritants in the air.
How to Assess Your Moisture Barrier
You can self-assess the strength of your moisture barrier by paying attention to your skin. "Skin might look and feel rough, dull, flaky, inflamed, red, and itchy," says Mark, although he points out that there can be other causes for those symptoms as well. The same lifestyle factors that can affect your skin overall can damage the moisture barrier: Not drinking enough water or drinking too much alcohol or caffeine. Environmental factors, like too much sun or wind, can also be damaging. You can also damage your moisture barrier by, not surprisingly, not moisturizing enough.
Can You Actually Repair Your Moisture Barrier?
Thankfully, most of those products that promise to "repair the moisture barrier" are probably helping. Mark recommends his patients stay hydrated on the inside and out, which means drinking lots of water and choosing the right skin care. "Apply products that include ingredients such as hyaluronic acid, which binds water up to 1,000 times its weight, and lactic acid, which is a humectant, meaning it actually increases the moisture content of the skin," he says. You'll know your barrier is on the mend when skin has less of those above symptoms, such as flakiness, roughness, and itchiness.
Just one caveat: A moisture barrier can be tricky to repair with home care if there is an underlying skin disease or severe skin damage, says Guanche. Visit your dermatologist, who can analyze barrier function using a measurement called Transepidermal Water Loss (TEWL). In the meantime, just keep moisturizing.
More on skin care:
- I Want an Elaborate Skin-Care Routine, But My Face Just Can't Take It
- How to Transition Your Skin-Care Routine From Summer to Fall
- The Dark Side of High-Tech Skin Care
Now, see how skin care has evolved within the last 100 years:
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