Polyhydroxy Acids (PHAs)

Organic compounds that, together with AHAs, retinoic acid (vitamin A), and ascorbic acid (vitamin C) belong to the class of so called carboxylic acids. There are different types of PHAs and they occur in nature. Some of them (for example, glyconic acid) can be found in our skin, and are a major component of synthesis of skin’s natural moisturizing factors (such as hyaluronic acid).

PHAs are typically are water-soluble, which means that the products that contain them are more likely to have a watery rather than oily texture.

In skincare, bionic acids (for example, lactobionic and maltobionic acids) are often mentioned as PHAs, even though technically they are in their own group.

In terms of skin goals, PHAs can help with:

  • Dry skin
  • Signs of aging, such as lines and wrinkles, and age-related large pores
  • Uneven skin tone and preventing hyperpigmentation
  • Preventing clogged pores and blemishes, and calming down inflammation
  • Help speed up the skin turnover revealing a smoother and more even complexion (so called “chemical” exfoliation even though technically PHAs do not work as exfoliants on the very surface layer of the skin).
  • Help neutralize free radicals, decreasing the damage from sun exposure and pollution.
  • Help attract water to the upper layer of the skin. Lactobionic (link) and maltobionic (link) acids especially are excellent moisturizing ingredients because they can form a gel-like moisture-rich matrix that can protect and hydrate skin over time.
  • Might be able to stimulate the production of skin’s own moisturizing factors, including hyaluronic acid, improving skin’d hydration and barrier function.
  • With regular use (2 months +), it can help stimulate collagen production in skin helping to reduce fine lines and wrinkles.

PHAs are considered to be more gentle to the skin and might cause less irritation compared to AHAs. There is no conclusive evidence for this yet though.

  • PHAs work well together with other active ingredients, for example, azelaic acid to calm down irritation and redness.
  • As with all active ingredients, concentration is important. Most clinical studies that documented a skin improvement as the result of PHA application used concentrations of 5-15%.
  • Anti-aging and brightening effect of PHAs only kicks in after a few weeks of consistent use - so you’d need to be patient.