We try to do the right thing. We wash our faces at night. We wear sunscreen (yes, even on cloudy days). And we slather our skin with ingredients that will trick it into acting younger. Now, we find out it needs something called a balanced pH. Sheesh. Like we don’t have enough to worry about? Not one to shy away from jargon, we’ve reached out to our most trusted experts for some insight onto the letters popping up on beauty packaging. What exactly is pH? Bear with us while we conduct a brief chemistry class: pH stands for “potential hydrogen” and describes the acid-alkaline ratio of substances. It’s a scale that ranges from 0 (battery acid) to 7 (water) to 14 (household bleach). The reason it matters: for our skin barrier — referred to by derms as the acid mantle — to be healthy, we need just the right balance between acidity and alkalinity (to be exact, it’s 5.5). "The outer layer of the skin needs to be slightly acidic to maintain skin-barrier function and ward off infection and toxins,” says Doris Day, a clinical associate professor of dermatology at the New York University Langone Medical Center. In other words, keep the good stuff in and the bad stuff out. So, how do you know if your skin is in its happy (naturally acidic) place? You could measure it (unleash your inner science nerd and buy a kit) or just look in the mirror. “Skin with a balanced pH looks healthier and hydrated, without flaking or redness,” says Day. Most of the time, our skin returns to this sweet spot on its own. “Skin care products with a pH higher than 5.5 will temporarily bring up the pH in your skin. Guess what? So will the water used to wash your face!” says cosmetic chemist Ni’Kita Wilson. “The skin is able to regulate these small variations — if it couldn’t, we’d be having major issues every time we stepped out of the shower.” Sometimes, however, due to environmental stress or the wrong skincare, our skin pH moves too far away from that 5.5 and doesn’t bounce back. What happens then? When skin is too alkaline, it feels dry and sensitive, and may even age faster (gulp). A study in the British Journal of Dermatology that tracked women's skin over an eight-year period found that women with an alkaline stratum corneum had more fine lines and crow's feet — and were more prone to sun damage — than those with acidic skin. At the other end of the spectrum, overly acidic skin has angry breakouts and may be inflamed and painful to touch.
A couple of factors alter our skin’s acidity. A big one — which sounds perfectly innocent — is washing your face with a little soap and water. If you’ve ever removed your makeup with a bar soap in your boyfriend’s shower (no judgement — we’ve all been there), that tightness you feel afterwards is because soap is naturally alkaline (between 9 and 12 on the scale). It strips away dirt and makeup, plus all the good stuff too, like natural oils. Most face washes (even basic ones like Dove White Beauty Bar) have both alkaline detergents, like sodium laurel sulfate, and acids, like citric or glycolic. Some formulas list pH levels on the label (like La Roche-Posay Effaclar Purifying Foaming Gel). You can also look for formulas labeled “soap-free” (such as Dermalogica Special Cleansing Gel) or “pH-balanced” (like Skin Doctor pH Balancing Cleanser). But don’t panic if your current cleanser says none of these things: “Most face cleansers are balanced and have the right pH — you’d know if it didn’t,” says Wilson. Guess what also makes our skin less acidic — getting older. “As our skin ages, it’s unable to maintain acidity, so our face can start to feel dry and itchy,” says Dr. Day, noting that moisturizers with alpha-hydroxy acids (like Philosophy Hope In a Jar Night) can lower pH levels again and help strengthen the skin barrier. At-home glycolic peels (preferably with a neutralizing step, like the ones from Dennis Gross MD, which prevent skin from traveling too far the other way) can also get you back into that sweet acidic spot. As for whether we should rush out and add “pH-balancing” formulas to our skin regimen, cosmetic chemist James Hammer says it’s not necessary. “It’s an important area to consider when it comes to skin care, but that is often happening in the lab when the product is formulated,” he says. “This is not a new idea. Any time a moisturizer or cleanser is made, one of the factors a chemist must consider is the pH — otherwise, it just won’t perform.” More good news: Hair is also slightly acidic — and the cosmetic chemists mixing up your shampoos and conditioners are all over it. “We’ve known for ages that to prevent hair from feeling dry and looking dull, we have to balance the pH with acidic ingredients,” says Wilson. If you’re worried, look for “sulfate-free” or conditioning formulas. The number-one factor that disrupts hair pH is permanent chemical treatments — "But many are now ammonia-free, which results in a milder pH," says Wilson. “And conditioning treatments can also minimize the damage.” So, there you have it. While pH is critical to skin health, avoid bar soap and give your skin the odd at-home peel. Let chemists worry about the rest.