A collage of different PHA skincare products, including a woman posing with a face mask.

A guide to polyhydroxy acid (PHAs) in skincare, the gentler exfoliating acid

Posted by for Skincare

Ever found the process of exfoliating irritating on your skin? Polyhydroxy acids, also known as PHAs, could be the answer. Here, we break down everything you need to know.

Skincare acids. They can be scary and intimidating – and that’s before you even get into the names.

You’ve likely already heard of alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs). As each is often buffered with a caution warning, though, you may have avoided using them in the past for fear of burning your face. But now, a third acronym is climbing the ranks in skincare as one of the market’s buzziest acids. Enter: PHAs, formally known as polyhydroxy acids.

PHAs are chemical exfoliants that work to buff away dead skin cells and leave skin smoother and brighter. Despite their effectiveness, PHAs are known as the gentler alternative to AHAs and BHAs. You see, PHAs have a large molecule size, meaning they exfoliate at surface level and don’t penetrate skin too deeply. The result is a more even skin tone and texture without the irritation.

Intrigued? Here, Dr Ifeoma Ejikeme, founder and medical director of Adonia Medical Clinic, runs through everything you need to know about PHAs.

What are PHAs?

“Polyhydroxyl acids are exfoliating acids which are more hydrating and less irritating than AHAs. They include lactobionic acid and gluconolactone acid and can be found in cleansers or as a leave on serum.”

What are the benefits of PHAs?

“These are exfoliating acids which help to exfoliate the uppermost layer of the skin, which helps to refine the appearance of pores and brightening the skin.”

How do PHAs differ to AHAs and BHAs?

“An alpha hydroxyl acid (AHA) is an exfoliating acid. Common options are glycolic acid from sugar cane, lactic acid from milk and mandelic acid from bitter almonds.

Beta hydroxyl acids (BHAs) are salicylic acid. This is best for oily and acne-prone skin. It has antibacterial and anti inflammatory properties.

“PHAs work in a similar way to AHAs but the molecular size is slightly larger which means it stays closer to the surface of the skin [making it more gentle].”

Which skin types are best suited to PHAs and which skin types should avoid using it?

“PHAs are great for those with sensitive skin. Anyone who has a breached the skin’s barrier function should first hydrate the skin and identify the reason for sensitivity before exfoliating their skin.”

Are there any side effects to PHAs?

“Almost any skincare ingredient used incorrectly can cause irritation so when starting an acid, I usually recommend you go slow and only start one active at a time to prevent irritation to the skin. There are formulations that combine acids which can be very good but use them as directed.”

Best skincare products with PHAs, picked by Stylist

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