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Countless beauty brands spend billions every year to make products that “smooth away” wrinkles — with sometimes impressive but always limited results.

Polyhydroxy acids (PHAs) are one of the latest trendy beauty ingredients touted to banish fine lines.

Older studies do suggest that PHAs can help hydrate skin and boost skin cell regeneration, which helps reduce the appearance of fine lines and wrinkles. Compared to similar exfoliating ingredients, they’re less irritating, especially if you have sensitive skin.

Here’s what you need to know about PHAs, including how they work, how to use them, and where to find them.

Aging has multiple effects on your skin: The epidermis (i.e., the skin’s outermost layer) thickens. The skin holds in less moisture and contains less collagen. Sun exposure further damages cellular DNA. Together, these factors increase the appearance of wrinkles.

PHAs are a chemical exfoliant.

“Exfoliation helps to slough away dead, dull-looking cells, reveal healthy cells, reduce hyperpigmentation, and improve skin texture,” says Dr. Dendy Engelman, a dermatologist practicing at Shafer Clinic in New York City.

PHAs also hydrate skin. They support the skin’s barrier function, which locks in moisture and reduces the appearance of fine lines and wrinkles.

The ingredient boasts other benefits too.

“PHAs potentially facilitate the penetration of other active ingredients applied to treated skin,” says Dr. Tsippora Shainhouse, FAAD, a board certified dermatologist in private practice at SkinSafe Dermatology and Skin Care in Beverly Hills, California.

And PHAs have antioxidant properties that “help undo and prevent UV and pollution-induced free radical damage to collagen and skin cells,” she says.

The result? PHAs have an anti-aging effect, says Shainhouse.

According to Dr. Peterson Pierre, a dermatologist with the Pierre Skin Care Institute in Westlake Village, California, common PHAs used in skin care products include:

  • gluconolactone
  • lactobionic acid
  • galactose

Are PHAs better for sensitive skin than BHAs or AHAs?

PHAs are a type of hydroxy (or fruit) acid. Other hydroxy acids include alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs).

All three are added to skin care products to help reverse sun damage, reduce the appearance of wrinkles, and make skin more elastic, toned, and hydrated.

However, PHAs may be less likely to irritate sensitive skin.

AHAs, including glycolic acid and lactic acid, are frequently added to skin care products to treat acne, scars, dark spots, dryness, and wrinkles. (Glycolic acid has the smallest particle size of all hydroxy acids, so it’s the best exfoliant, Engelman adds.)

BHAs, such as salicylic acid, are anti-inflammatory. They’re often recommended for oily or acne-prone skin, say Engelman and Shainhouse.

That said, these ingredients aren’t for everyone.

AHAs are known to cause swelling and burning, and may make your skin more sensitive to the sun.

While BHAs may be slightly less irritating than AHAs, the Food and Drug Administration (FDA) warns they still make skin more sun sensitive.

“Although AHAs and BHAs are fantastic and have many benefits for the skin, they can definitely be harsh and cause some irritation,” Pierre says.

Some research suggests PHAs are almost as effective as the other hydroxy acids and less likely to irritate your skin. That means you’ll probably tolerate them better if your skin is extra sensitive, or if you have conditions like rosacea or eczema.

“I like PHAs because it acclimates the skin to exfoliation with little risk of irritation,” Engelman says.

For example, a 2004 study (paid for by a cosmetic company) compared gluconolactone-containing PHAs to glycolic acid-containing AHAs over 12 weeks. Researchers found that both ingredients had anti-aging benefits, but that PHAs were less irritating.

“PHAs have a larger molecular structure than AHAs and BHAs, which means they take longer to penetrate and won’t penetrate as deeply,” Engelman says.

Shainhouse adds that PHAs may be associated with less post-treatment sun sensitivity and risk of sunburn and sun damage.

Another 2004 study found that the PHA gluconolactone prevented some UV damage in mouse skin cells.

The same researchers also tested PHAs on people. They found the ingredient didn’t increase risk of sunburn, suggesting it may be a better option than AHA or BHA for people with sensitive skin.

Still, PHAs aren’t for everyone. If you find that your skin is sensitive to the ingredient, Pierre says to avoid it.

“Otherwise, they’re great for all skin types, even if you’re pregnant or breastfeeding,” he says.

PHAs are found in cleansers, toners, pads, masks, and even moisturizers.

Engelman prefers PHA pads.

“It gives you the correct dosage in a clean, sterile delivery system,” he says.

Pierre argues that serum or creams give maximum results.

“PHAs need time in contact with the skin for you to see their beneficial effects,” he explains.

No matter which product you choose, follow these tips.

Check the label

Scan for one of the following PHAs:

  • gluconolactone
  • lactobionic acid
  • galactose

Consider combining with AHAs or BHAs

If your skin tolerates it, choose a product that combines PHAs with AHAs, BHAs, or both. “They can do a better job and deliver better results,” Pierre says.

“Some of my favorite chemical exfoliants have a mix of AHAs, BHAs, and PHAs,” Engelman says.

If you have extra-sensitive skin, PHAs alone may be your best bet. “They are great for all skin types, especially those with sensitive skin… [and] are gentle enough to use even if you have rosacea or eczema,” Pierre says.

Don’t overdo it

Although many serums use a combination of AHAs, BHAs, and PHAs, “those are safe because they are specifically formulated to be used together,” Engelman says.

Don’t buy separate chemical exfoliant products and use them together. Doing so can overwork and thin the skin, breaking down the bonds of healthy cells, Engelman adds.

Pair with a barrier builder

To strengthen the skin barrier, Engelman and Shainhouse suggest looking for a PHA product that contains:

  • ceramides
  • hyaluronic acid
  • glycerin
  • peptides

Or pair your PHA exfoliant with another skin care product that contains these ingredients.

“PHAs have hydrating properties, which could be amplified by combining them with other moisture-locking ingredients,” Shainhouse says.

Test it first

Before you smear a new PHA product all over your face, test it out on your forearm first. If it doesn’t irritate your skin after 24 hours, incorporate it gradually into your regimen.

Use as needed, but watch for irritation

Pierre suggests using a new PHA product on three nonconsecutive days a week. Gradually increase the frequency as long as your skin tolerates it.

Ultimately, take your skin’s reaction as a cue. You might be able to use a cleanser, moisturizer, toner, or pad daily. Or you might find you’re better off using toners and pads weekly, says Shainhouse.

Always follow the instructions on the label. Most masks, for example, are meant to be used once per week or once per month, Shainhouse says.

Apply after washing and before moisturizing

Engelman says you can use a PHA product either in the morning or at night after washing skin.

“As with most exfoliating treatments, PHA masks and peels are best applied to clean skin,” Shainhouse says.

Always follow with a serum (if you use one) and moisturizer to seal in the hydration and protect the skin barrier.

Don’t forget to finish with a broad spectrum sunscreen during the daytime to prevent sunburn, adds Shainhouse.

Be cautious with certain ingredients

Because PHAs are an acid, they shouldn’t be combined with pH-sensitive ingredients.

“This includes vitamin C, which is a very unstable molecule,” Shainhouse says. Instead, apply vitamin C serum in the morning and your PHA exfoliant at night.

And as long as it doesn’t bother your skin, some research suggests retinyl acetate (vitamin A) may enhance the effects of PHA. Just don’t apply products containing these ingredients at the same time to avoid irritating your skin, Shainhouse says.

For extra-sensitive skin, you may also want to try alternating between PHA and retinoids every day, suggests Engelman.

Engelman recommends the following PHA products:

  • Elizabeth Arden Prevage Progressive Renewal Treatment.This 4-week, at-home peel “provides excellent gentle exfoliation with AHAs and PHAs, leaving skin feeling smooth,” Engelman says. He suggests using it once every few months.
  • Glo Skin Beauty Pro 5 Liquid Exfoliant. “This peel combines AHAs and PHAs for an effective yet gentle exfoliation. The skin will look brighter after one use,” Engelman says. The combination of mandelic acid, lactic acid, gluconic acid, malic acid, and tartaric acid are safe for all skin types, he adds.

Other recommended skin care products with PHA include:

PHA products can get a little pricey, but more budget-friendly options include:

PHAs, including gluconolactone, lactobionic acid, and galactose, are chemical exfoliants that hydrate skin and help reduce the signs of aging.

They’re less irritating and less likely to cause sun sensitivity than other chemical exfoliants. That makes them a better choice if your skin is sensitive or prone to rosacea or eczema.

If it doesn’t bother your skin, choose a product that combines PHAs with either BHAs or AHAs for the best results. Apply on clean skin and follow up with moisturizer.