What are PHAs?

PHAs, polyhydroxy acids, are the most modern generation of chemical exfoliants. They belong to the same family as AHAs (alpha-hydroxy acids like glycolic acid) but have a key structural difference: their molecules are larger, which means they act more slowly and superficially, without penetrating into the deeper layers of the skin. The result is effective and progressive exfoliation with a very low irritation profile.

They are obtained by fermentation of plant-derived sugars. The most common in cosmetics is gluconolactone, derived from corn glucose, with exceptional skin tolerance even for very reactive skin types.

How do PHAs work?

They act on the outermost layer of the skin, promoting the natural shedding of dead cells, without attacking the deeper layers. Unlike AHAs, they do not aggressively accelerate cell renewal; they accompany it. This eliminates the risk of irritation, flaking, and photosensitivity that can occur with more potent exfoliants.

In addition to exfoliating, PHAs have their own humectant function: they attract water to the skin's surface and help keep it more hydrated and comfortable after exfoliation. They do not dry out the skin. On the contrary.

PHA, AHA, and BHA: What's the difference?

All three are chemical exfoliants but with very different profiles. AHAs, like glycolic or lactic acid, have small molecules that penetrate deeper and work more intensely on texture and tone. They are effective but require more adaptation and sun precaution. BHAs, mainly salicylic acid, are oil-soluble and penetrate the pores, especially indicated for oily skin and imperfections. PHAs do less, but cause less discomfort. They are the option for those who need renewal without the cost of irritation.

Properties and Benefits

• Gentle and progressive exfoliation without irritation or photosensitivity. Suitable even for sensitive, reactive, or rosacea-prone skin.
• Simultaneous hydration. They exfoliate and moisturize at the same time, something that AHAs and BHAs do not do by default.
• Strengthening of the skin barrier. By working more superficially and respectfully, they do not compromise the skin's protective function as more aggressive exfoliants can.
• Antioxidant action. They help protect the skin from environmental oxidative stress.
• Improvement of texture and tone with continued use. Without the drama of adaptation.

Usage and Integration into Routine

They can be used morning and night, even daily, without the usage restrictions imposed by AHAs. They do not require additional specific sun protection, although, as with any exfoliant, daily sun protection is always recommended.

They are applied after cleansing and before moisturizer or oil. They combine particularly well with hyaluronic acidto enhance hydration and with niacinamideto address tone and barrier. With more potent exfoliants, it's better to alternate rather than combine in the same application.

Curiosities and Facts

Here to stay
PHAs arrived on the mass market when interest in chemical exfoliants had already created a problem: over-exfoliated, irritated skin with a compromised barrier due to excessive use of glycolic and salicylic acid. PHAs responded to that need with a more moderate and sustained approach. They are not the most potent exfoliant, but they are the smartest for regular use.

Pharmacy history
Gluconolactone has a medical history before a cosmetic one. It was used for years in pharmaceutical formulations for the care of skin with eczema and dermatitis, where tolerance is critical. Its arrival in general cosmetics was a consequence of that clinical trajectory, not the other way around.

Less known and more interesting
In terms of search volume and popularity, AHAs surpass PHAs. But in terms of versatility of use, tolerance, and compatibility with all skin types, PHAs win. An ingredient undervalued by marketing, overvalued by those who try it.

This is how it appears in the INCI: Gluconolactone, Lactobionic Acid, Galactose

Other active ingredients you might be interested in

Succinic acid: purifying and balancing exfoliant, same philosophy of skin respect.
Hyaluronic acid: deep hydration, ideal complement after exfoliation.
Niacinamide: balance, tone, and barrier, common combination with PHA in complete routines.
Beta-glucan: soothing and moisturizing, strengthens the barrier that the exfoliant works on.
Urea + PHA + HA Formula: to see how PHAs work in combination with other active ingredients in a real formula.