Polyhydroxy Acid Is The Miracle Skincare Ingredient You Never Knew You Needed

So, what are PHAs?

PHAs are second-generation AHAs. Just like alpha hydroxy acids and beta hydroxy acids, polyhydroxy acids are chemical exfoliants used to slough off dead skin cells on the surface, unveiling soft skin and improving texture in the process.  Not only does exfoliating make your skin look younger and brighter, but it also makes your entire skincare routine more effective. How so, you ask? By removing dead skin cells, dirt, and makeup that’s stuck on the surface, you’re allowing your products to penetrate deeper within the layers of your complexion. The deeper the products can go, the more effective they’ll be. “They are popular for boosting the penetration of active ingredients and revealing smoother, brighter skin with antioxidant and anti-inflammatory properties,” says Jessie Cheung, MD, board-certified dermatologist and founder of Cheung Aesthetics & Wellness.

The most commonly found PHAs in beauty products include gluconolactone, galactose, and lactobionic acid. “They're rich in antioxidants and stimulate cellular repair,” says Rhonda Klein, MD, dermatologist and partner at Modern Dermatology in Westport, CT.

PHAs also fight glycation, which occurs when digested sugar attaches to a protein or lipid, weakening it and breaking it down. “The primary proteins in the skin that can suffer from this are collagen and elastin, which are responsible for maintaining our skin's structure,” says Dr. Klein. “Polyhydroxy acids prevent sugar from attaching to collagen and elastin proteins and support new collagen synthesis.” They also strengthen the skin’s barrier. 

What makes PHAs different from AHAs and BHAs?

The main difference between the acids? “They are gentler as they do not penetrate as deeply,” says Dr. Klein. The reason they can’t travel as far below the skin’s surface all comes down to their molecular structure. PHAs are made up of bigger molecules compared to AHAs and BHAs, which means they won’t travel as far below the skin’s surface. “They work in the upper layers of the skin, supporting the skin barrier itself to retain moisture levels and skin integrity,” says Dr. Klein. 

They also share similarities between the other two acid groups. Like BHAs, PHAs offer anti-inflammatory properties and, like AHAs, PHAs also have moisturizing properties. “They are humectants, which means they draw moisture into the skin,” says Dr. Klein.

You’ll often find PHAs in products on their own or combined with AHAs and BHAs–they play well with one another when combined. Chances are, your glycolic acid cream or exfoliator already employs PHAs. “They can work synergistically with AHAs and BHAs but still have benefits on their own in more sensitive formulations,” says Dr. Klein.

What skin types can use PHAs?

Unlike other acids, PHAs are approved by use for pretty much everyone. “Anyone can use PHAs, since they're not known to cause irritation, but help to strengthen the skin's barrier function,” says Dr. Cheung.

If you have sensitive, dry skin and haven’t been able to tolerate chemical exfoliation in the past, PHAs can work wonders in your skincare routine. “They are ideal for more sensitive skin types that experience irritation from AHAs and BHAs,” says Dr. Klein. Now even those with sensitive skin can reap the benefits of chemical exfoliants without stinging or burning side-effects. 

They’re also a safe choice for anyone who suffers from a skin condition. “PHAs contain anti-inflammatory properties which may be really helpful to rosacea-prone skin,” says Dr. Klein. If you’re already incorporating acids in your routine, PHAs can enhance your results. Dr. Klein recommends alternating a PHA product with an AHA product every other night for a more gentle approach to what you’re already doing.

Chances are, they also might already be working their magic in an AHA product, retinol, or bakuchiol that you're already incorporating in your routine.  “Together they target the upper and lower level dead skin cells,” says Dr. Klein.

Are there any side effects?

Since PHAs aren’t traveling deep into your skin, they aren’t commonly associated with any side effects. In fact, they’re the most gentle of all the acids–but whenever you incorporate new skincare products in your routine you always run the risk of sensitivity. “If you are prone to irritation, try a patch test on a small area before using widespread,” advises Dr. Klein. 

From moisturizing and exfoliating to antioxidant properties and anti-aging benefits, polyhydroxy acids provide a gentle approach to chemical exfoliation for those who typically couldn’t tolerate using AHAs and BHAs in the past, making them a welcome addition to your skincare routine. 

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