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Guide to PHAs - Polyhydroxy Acids

  • 2 min read

Guide to PHAs - Polyhydroxy Acids

What are PHAs?


Polyhydroxy acids — aka PHAs — are chemical exfoliants, and are considered 'cousins' of alpha hydroxy acids, as they are, in fact, second-generation AHAs The most common PHAs are gluconolactone, galactose, and lactobionic acid.


Similar to AHAs, PHAs work by exfoliating dead skin cells on the surface, resulting in a more even skin tone and texture, and also help skin-care ingredients penetrate deeper into the layers of your skin, thus boosting their efficacy.


PHAs also fight glycation, a process that takes place when digested sugar permanently attaches to the collagen in your skin and can weaken it, along with elastin levels. They're also rich in antioxidants and stimulate epidermal growth and repair.


How are PHAs different from AHAs and BHAs?


The molecules of PHAs are much larger and therefore cannot penetrate as deeply as AHAs and BHAs; they work exclusively on the surface, without disturbing the deeper delicate layers. They offer less irritation than their acidic counterparts.


An additional benefit is that skin does not become more photo-sensitive, or susceptible to damaging UV rays.


Are PHAs suitable for my skin?


AHAs, such as glycolic acid and lactic acid, penetrate the skin more deeply, while BHAs like salicylic acid are better suited to oilier, acne-prone skin. AHAs are generally preferred for normal to dry skin, and are used due to their affinity to enhance natural moisturizing factors and exfoliate dead cells. BHAs, which are great for oilier skin types, work their way into blocked pores, dissolving sebum and dead skin cells, and help exfoliate acne that can lead to post-inflammatory pigmentation.


As for mixing acids together? Yes, it can be done. However, if that's a little strong for your skin, try taking things slow with either a PHA-based product like our Soothing Face Mist!


Sensitve Skin Types Benefit Best From PHAs


The unique properties of PHAs mentioned above — larger molecule size, surface level penetration — make them ideal for virtually all skin types, especially if you've experienced sensitivity in the past with an AHA- or BHA-based product. PHAs are wonderful alternatives to both AHAs and BHAs if you tend to have very sensitive, dry, or itchy skin and could not tolerate many chemical exfoliants. Additionally, PHAs are an attractive option for those with dry skin as they are humectants, meaning they attract water and are ultimately moisturizing.