Read The Label: All Your Polyhydroxy Acid Questions Answers

Polyhydroxy acids (PHAs) offer exfoliating benefits akin to alpha and beta hydroxy acids without the skin-sensitizing side effects. Here’s what the experts have to say.
Expert Opinion
Written by Vivien Moon
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Read The Label: All Your Polyhydroxy Acid Questions AnswersDean Drobot/Shutterstock

Feel like you need a dictionary every time you look at the ingredient list of a beauty product? Still unsure of the difference between retinol and retinoids? What about the unique benefits of vitamins B, C, and E? Are alpha and beta hydroxy acids the same thing? The skincare aisle can be overwhelming, but you don’t need a PhD in cosmetic chemistry to navigate it. With expert help, The AEDITION is demystifying and simplifying the beauty industry — one label at a time.

It’s no secret that chemical exfoliation (usually with an acid) has become the go-to technique for inducing cellular turnover, as the days of abrasive scrubs are behind us. Alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs) are two of the most recognizable and popular classes of acids in skincare, but it’s time to focus on their gentler – yet similarly effective – counterpart: polyhydroxy acids (PHAs). Often found in toners and at-home peels, PHAs may be the key to a brighter complexion for those with sensitive skin. Here’s what you need to know about the buzzworthy ingredient.

What Are Polyhydroxy Acids (PHAs)?

Polyhydroxy acids are a gentle chemical exfoliant with a larger molecular size than AHAs and BHAs, which means they cannot penetrate the skin as deeply. As a result, PHAs work more on the surface to improve skin tone and texture without sensitizing it. Needless to say, you can’t really have a discussion about PHAs without mentioning their cousins, AHAs and BHAs. While these exfoliating ingredients are closely related, they have some key differences:

  • Alpha Hydroxy Acids (AHAs): “AHA is a water-soluble acid and includes glycolic acid, lactic acid, malic acid, citric acid, and tartaric acid,” explains Miwon Kwon, senior product developer at JOAH Beauty. “It helps to remove dead skin cells and maintain skin moisture.”
  • Beta Hydroxy Acids (BHAs): “BHA refers to salicylic acid as a fat-soluble ingredient and helps remove sebum and dead skin cells,” she says. “BHA is common for oily skin,”
  • Polyhydroxy Acids (PHAs): “PHA is a water-soluble ingredient and less irritating exfoliating ingredient,” Kwon notes. This allows for PHAs to be formulated in a variety of ways — but more on that later.

While the term ‘BHA’ in skincare primarily refers to salicylic acid, there are a number of acids that fall under the AHA umbrella. PHAs are similar in that respect. Here’s what to look for in the ingredient list:

  • Gluconolactone
  • Lactobionic
  • Galactose

Gluconolactone is the acid most often found in skincare products and may be written as ‘gluconic acid’ on the label. It also functions as a humectant due to the multiple hydroxyl groups that allow them to carry more water weight.

What Are the Benefits of PHAs in Skincare?

Polyhydroxy Acids PHAs Skincare Benefits Infographic

As an exfoliator, PHAs help rid the complexion of dead skin cells, reduce the appearance of sun damage and pigmentation, and repair the skin. PHAs are beneficial for those whose tolerance of other chemical exfoliants (think: AHAs and BHAs) is low but who still want an exfoliating effect.

In a study comparing AHAs and PHAs (specifically glycolic acid and gluconolactone), PHAs were found to have similar anti-aging benefits to AHAs. Although glycolic acid had better results, the margins were not drastic enough to sideline gluconolactone. PHAs also work similarly to antioxidants by helping to minimize signs of aging without irritation. As a result, they are beneficial for people of all ages.

Who Are PHAs Good For?

As mentioned previously, those with sensitive skin will likely appreciate the gentle-yet-effective nature of PHAs the most. “The unique properties of PHA – larger molecule size, surface-level penetration – make them ideal for virtually all skin types,” explains Amy Spizuoco, DO, a board certified dermatologist and founder of True Dermatology in New York City. This includes people with sensitivities, rosacea, and eczema, because “PHAs are a reparative ingredient,” she says. But that’s not all. PHAs can also prove to be an effective acne treatment for some.

How to Find the Right PHA Product

Today, PHAs can be found across the beauty aisles in products like face masks (OleHenriksen PHAT Glow Facial is a favorite), toners (hi, Glossier Solution), and exfoliating pads (the JOAH Beauty Daily Glow Peel Pads pair PHAs with 5 percent AHAs). Here’s what to keep in mind when considering a PHA product:

  1. Prioritize Percentage: Dr. Spizuoco recommends staying in the 10 percent range, but a lower concentration should not disqualify the product — especially if it’s formulated with complementary ingredients.
  2. Consider the Formula: As with any acid formulation, PHAs tend to work best as leave-on toner solutions, serums, face creams, and lotions because they allow the ingredient to fully absorb into the skin and provide maximum benefits.
  3. Read the Label: Additional ingredients paired with the PHAs should also be examined to enhance skin health. In the Peter Thomas Roth PRO Strength 10% PHA Exfoliating Clarifying Liquid, for example, PHAs are blended with 5 percent glycolic acid, 0.5 percent salicylic acid, ceramides, and a proprietary lipid complex. The result? A glow-inducing treatment that also balances and hydrates.

Reading the label doesn’t just mean looking for the names of ingredients. “We look for innovation — which could be an unexpected way in which the product should be used — and ingredients that are not only supported with clinical testing but at the percentage recommended by the original manufacturer,” explains Chelsea Scott, co-founder of The Beauty Spy. “We need to ensure the combination of ingredients and innovation provides the promoted benefits.” Kerry E. Yates, beauty expert, inventor, and founder of Colour Collective, agrees. “There are FDA requirements for labeling, so brands have to be very careful if they fail to list their ingredients correctly,” she says. “If claims seem too good to be true, they are probably false.”

When To Use PHAs

If you’re ready to give PHAs a go, start with a patch test (the inner arm or jawline are usually good spots) before slowly integrating them into your routine. “Think once every two to three days,” Dr. Spizuoco says. And be sure to speak with your dermatologist about the best way to incorporate them based on your skin type. “PHAs can be combined with other ingredients or dermatologic procedures to provide additional benefits,” she explains. PHAs can be paired with retinoids when treating acne or photoaging; or they can be used in conjunction with hydroquinone to improve skin pigmentation and aging.

For Scott, PHAs are a friendly ingredient that don’t negate the effects of many others. “Because they’re mild, it’s safe to use your PHA products with most other products in your skincare regimen, like toners, moisturizers, and serums,” she says. Even those who are concerned about their post-procedure skincare can feel comfortable reaching for polyhydroxy acids. “PHAs may also be used after cosmetic procedures, such as lasers and microdermabrasion, but should be done in consultation with your dermatologist,” Dr. Spizuoco notes.

Unlike AHAs, which are often recommended for nighttime routines, PHAs are usually given the green light for morning use. “Studies show evidence that gluconolactone can neutralize free radicals to combat UV damage, which may be attributed to its chelating properties that allow it to bind to skin-damaging free radicals caused by exposure to things such as sun and pollution,” Dr. Spizuoco explains. “PHAs don’t increase the number of sunburned cells or make your skin more sensitive.”

The Takeaway

Whether you have sensitive skin or are simply looking for another acid to add to your chemical exfoliation regimen, polyhydroxy acids can address uneven skin tone and texture concerns for a wide range of skin types. Remember to always consult with a dermatologist or skincare expert before adding a new ingredient to your routine.

All products featured are independently selected by our editors, however, AEDIT may receive a commission on items purchased through our links.

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VIVIEN MOONis a senior editor at AEDIT.

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