Everything you need to know about the buzzy acid in town: PHAs

For years, dermatologists, skincare enthusiasts, blogs and brands have preached the gospel of acids to anyone who will listen. And thanks to the vast amount of information that's currently at our fingertips, the average beauty fan now knows an impressive amount about the science behind what they're putting on their face.

These days, you'd be hard-pressed to walk into a Sephora and find someone who doesn't know that hyaluronic acid is a moisturizing hero; that AHAs (alpha hydroxy acids), such as glycolic and lactic acid, are great exfoliants; and that a BHA (beta hydroxy acid), like salicylic acid, can be helpful for acne.

So when some major skincare launches popped up recently touting PHAs, or polyhydroxy acids, as a star ingredient, we knew we had to learn more about AHAs' and BHAs' lesser-known sibling. We chatted with dermatologist and founder of Toronto's Bay Dermatology Centre Dr. Sandy Skotnicki to find out everything we need to know about polyhydroxy acids.

It turns out, PHAs are quite similar to AHAs. "The benefits of AHAs on skin — exfoliation, smoothing, and anti-aging — were discovered by Dr. Eugene Van Scott and Dr. Ruey Yu in the early 1970s," says Dr. Skotnicki. "PHAs provide similar effects as AHAs … They can also act as a humectant [meaning they draw moisture out of the air and into skin] and moisturizer, and improve skin barrier function."

The most common types of PHAs are gluconolactone and lactobionic acid. Both promote cell renewal, have antioxidant effects, and can help even out and brighten skin.

So how are they different from AHAs and BHAs? "PHAs are functionally similar to AHAs, but they have a larger molecular structure," explains Dr. Skotnicki. "This means they can't penetrate the skin [as much as] AHAs and BHAs, which results in less skin irritation."

For this reason, PHAs may be a better choice for sensitive or reactive skin types than AHAs or BHAs. PHAs are also an alternative for those with darker skin tones. "[When some] AHAs or BHAs cause irritation in darker skin, it can lead to pigmentation changes," says Dr. Skotnicki.

Below are some of our favourite skincare products made with PHAs.

Instagram's current favourite sleeping mask blends avocado extract, manuka honey, kaolin clay and a PHA (gluconolactone) to gently exfoliate and moisturize skin while you snooze. You'll wake up with brighter, firmer skin.

Glow Recipe Avocado Melt Sleeping Mask, $59, sephora.ca

Glossier's first foray into acids came at the beginning of 2018 with Solution. This chemical exfoliator features a 10 per cent blend of alpha, beta and polyhydroxy acids that gently sloughs away dead skin for fewer blackheads, smaller-looking pores and evened-out skin tone.

Solution, $29, glossier.com

This just-launched night cream also uses a blend of the three acid groups to exfoliate overnight. It also features cationic technology, meaning the positively charged formula is attracted to the negative surface of skin. The addition of passion fruit oil means this is one product you'll definitely want to smell for yourself.

Glamglow Good In Bed Passionfruit Softening Night Cream, $75, sephora.ca

This soap-free gel cleanser is great for those with sensitive skin. It features four per cent gluconolactone to gently exfoliate while you wash, without irritating. It's also gentle enough to use daily, since it won't compromise your skin's moisture barrier.

Neostrata PHA Facial Cleanser, $33.49 (on sale for $25.11), well.ca

Formulated with three per cent PHA to exfoliate, fifty per cent coconut fruit extract to moisturize and two per cent niacinamide to brighten, this all-in-one night cream can be used as a 10-minute mask or left on overnight.

PHA Moisture Renewal Power Cream, about $34 CAD, sokoglam.com

Souzan Michael is a Toronto-based writer and editor with a deep, undying love of astrology, watermelon and golden retrievers. Follow her on Instagram @suziemichael_.