Gluconolactone (PHA)
The most widely used PHA: the gentlest kind of chemical exfoliant, which smooths and hydrates sensitive or dry skin.
gluconolactone, glucono-delta-lactone, PHA, polyhydroxy acid, poly hydroxy acid, lactobionic acid
Sensitive skin · Dry & dehydrated skin · Texture & large pores · Dull skin
What it does
Gluconolactone is the most widely used of the PHAs, or polyhydroxy acids, the gentlest family of chemical exfoliants. Lactobionic acid is the other PHA you are likely to see on labels. Both appear in toners, essences, peels and masks for sensitive or dry skin, and gluconolactone is one of the acids in Biologique Recherche Lotion P50. It is sometimes confused with glucuronic acid, a sugar acid best known as one of the building blocks of hyaluronic acid, which is used in skincare as a hydrator rather than an exfoliant.
How it works
PHAs work in a similar way to AHAs, loosening the bonds between dead cells on the skin's surface, but their larger molecules penetrate more slowly and superficially, so they are far gentler on the complexion. They also attract moisture to the skin and have antioxidant properties. For this reason, PHAs are best suited to sensitive, dry or damaged skin, and will help gently buff away the surface of the skin to deliver a small amount of exfoliation.
MG says
For skin that is too sensitive for AHAs or BHAs, PHAs are the gentlest way to exfoliate; if your skin is very reactive, start with a low concentration once a week or less. I love Augustinus Bader The Essence, which pairs gluconolactone with hydrators and soothing botanicals, to prep, balance and refine the skin in one simple step.
Cautions
PHAs are gentle, but they are still exfoliants: introduce them slowly and don't layer them with other acids or retinoids on the same night. Stop if you see persistent redness, stinging or flaking, and, as with any exfoliating routine, use a broad-spectrum sunscreen daily and for a week after use.
