PHAs in skincare: 9 things you need to know about Polyhydroxy acids 

Updated: May 7, 2020

Step aside AHA and BHAs, because there is a new hydroxy acid in town.  

PHAs, or more commonly known as polyhydroxy acid act like any other skincare acid we know of – it provides a chemical exfoliation to the skin. This game-changer of a skincare ingredient was discovered just under thirty years ago, due to strict patenting guidelines, the acid has been notoriously expensive to use in skincare manufacturing. Recently these patents have expired and allowed a flourish of research and skincare brands experimenting with this multi-tasker star ingredient. Use this post to guide you through everything that you need to know about PHAs and how you may benefit from using this gentle exfoliator.

PHAs are cousin to AHAs

Polyhydroxy acid work similarly to AHAs (such as glycolic, malic, tartaric and lactic acid) where they exfoliate the skin’s surface by breaking down the ‘glue’ that holds on to the dead skin cell. Thousands of studies have shown how by using hydroxy acids regularly in your routine, it can stimulate the cellular turnover in the skin, helping improve a multitude of concerns from dryness, fine lines, uneven skin tone and texture and hyperpigmentation to name a few. 

slay hair model flip gif

via giphy

Polyhydroxy acids are suitable to use on sensitive skin

One great thing about PHAs is that they have a much larger molecule structure, which means that the product isn’t able to penetrate the skin as much in comparison to AHA and BHA formulations. This superficial effect limits the chances of irritation, whilst still proving an effective enough exfoliation for the skin. 

Why is this such a positive? Because PHAs are gentle enough to use on sensitive skin types. Despite the common hype that has developed around the idea of using hydroxy formulas, it doesn’t cancel out the amount of people that do develop sensitivities and reactions towards using acid-based products. Polyhydroxy acid-based formulas hold a very small chance, if any, of creating irritation in the skin so are a more reliable choice to gravitate towards if you are a) new to using skincare acids or b) have experienced reactions to hydroxy skincare products in the past. 

samantha jones skin peel


PHAs were founded in the 90s

Fun fact. Dr Van Scott and Dr Yu patented the discovery of PHAs in 1994 for the world-renowned Canadian skincare brand Neostrata. Interestingly this was also the same company to have first identified how AHAs work in skincare just a couple of decades before.

neostrata our story screenshot

Screenshot: Neostrata

PHAs are humectants

You may have heard of humectants in skincare before. It’s a profound ingredient found in personal products like cleansers, eye creams and shampoos, due to its ability to moisturise the skin, because of its magnet-like structure to attract and retain water. 

Humectants pull the water from the dermis (the second layer of skin) to the epidermis (the top layer), which increases the moisture on the surface, reducing the appearance of dryness, general dehydration and flaky, dead skin cells.  

jimmy fallon happy dance

via giphy

They fight glycation

Glycation is the process of when digested sugar in the human body becomes attached to protein, which then causes the fibres to become rigid and ill-formed. This is always disastrous for collagen and elastin in the skin (both are technically proteins) and can lead to the appearance of dull, sagging skin. 

Of course, this is a difficult process to steer away from – after all it seems that sugar is everywhere, and impossible to avoid in our diets. But it’s not all bad because PHAs in skincare can actually reduce this glycation activity. 

There are two names you need to remember

There are two types of polyhydroxy acids you need to know the name of, that are used in the skincare on the market today. They are: 


This is a powerful humectant and also plays an antioxidant role in the skin. Glyconolactone is simply oxidised glucose, a natural sugar that serves the body’s main source of energy. Studies have shown how it nourishes the skin’s barrier by preventing moisture loss, but also effectively resurfaces the skin leading to improvements in hyperpigmentation, texture and fine lines. 


This ingredient also acts as an antioxidant and is derived from milk sugars. It is a safe, gentle PHA, commonly used in organ transplantation to preserve fluids during operation.  

applying moisturiser

via pexels

PHAs can effectively treat rosacea, eczema and dermatitis

Because polyhydroxy acids have a larger molecule structure and therefore work superficially on the skin, it means that they can safely treat and resurface irritating, dry skin conditions such as eczema, rosacea or psoriasis. In most cases, this causes a great build-up of dead skin cells because of the excessive dryness, and requires exfoliation more than the next person – studies have proven how PHAs are a great thing to use to do this.  


via flickr

Did you know 1 in 5 children in the UK will suffer from eczema at some point in their lives?

PHAs should not be used on oily skin types

There is one thing that PHAs are no good for and that is oily skin types and acne. Polyhydroxy acids as we know, work superficially and are incredibly moisturising, which is the last thing an oily skin needs. Instead, choose BHAs (like salicylic acid) that can work more effectively on the P-bacterium and at a deeper level in the skin. 


via giphy

You can mix PHAs alongside other hydroxy acids

It is safe, and also common to use a combination of hydroxy-based skincare products because then you can treat a variety of concerns. AHAs are great for normal to dry skin types, BHAs for oily skin types. Why would you not want to use a product like Glossier’s Face Exfoliator and Skin Perfector, that uses all three hydroxy acid groups, to address all of your concerns?  


via aestheticsurge

PHAs are great for all skin types but will particularly benefit dry and sensitive types due to their ability to moisturise and gently exfoliate the skin. Is there anything polyhydroxy acids can’t do? They act as an antioxidant, protect the skin’s barrier, encourage the skin’s cellular turnover and wound healing, and even treats inflamed skin conditions such as eczema and rosacea. You can use PHAs alongside BHA and AHA-based skincare products and daily, due to their limited ability to create irritation in the skin. Polyhydroxy acids can be found in cleansers, creams and toners, lotions and essences, and I would recommend to specifically choose a serum for better absorption and results. 

Why not try?

Neostrata Intense Anti-ageing Bionic face serum

Contains: 10% Lactobionic acid 

£32 for 30ml at LookFantastic

Neostrata antioxidant defense serum

via Caroline Hirons

Medik8 White Balance cleanse

Contains: Gluconolactose  

£35 for 75g at Medik8


via Medik8

Alumier MD Enzymatic peel 10%

Contains: 10% lactic acid plus gluconolactose 

Find your nearest stockist here

alumiers enzymatic peel

via Alumiers

#AHAs #glycation #humectants #dryskin #hydration #hydroxyacids #eczema

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