PHA (lactobionic acid)

PHA · polyhydroxy acids · lactobionic acid · gluconolactone · acido lattobionico

Larger 'next-generation' exfoliating acids marketed as gentler alternatives to AHAs.

TypeCosmetic (topical)

The grade answers: What does the human evidence support for: Gentle exfoliation & hydration?

Grade

Limited

The grade rates evidence quality — it is not advice to take or buy.

Class: Skincare / topical
Primary use: Gentle exfoliation & hydration
Evidence strength: low
Last reviewed: 2026-07-01

Bottom line

The gentle cousins of AHAs: bigger molecules that exfoliate more mildly and add hydration and antioxidant character. Good for sensitive skin, but with a thinner evidence base than glycolic or lactic acid.

What the evidence says

Polyhydroxy acids (PHAs) such as gluconolactone and lactobionic acid are larger molecules than classic AHAs, so they penetrate more slowly and tend to be less irritating, while also acting as humectants and, for lactobionic acid, offering antioxidant/chelating properties. The evidence is more limited and often industry-linked compared with glycolic/lactic acid, and mostly points to good tolerability with milder exfoliation. This is cosmetic use, not a peel procedure, and product formulation decides the result. Grade C: a sensible gentle option, with modest independent data.

Key studies

[1]
Polyhydroxy acids in cosmetic use · review
Gentler exfoliation with humectant properties.
Open on PubMed ↗
[2]
Lactobionic acid antioxidant / humectant properties · review
Extra hydration and antioxidant character.
Open on PubMed ↗
[3]
PHA tolerability vs AHA · review
Milder profile suits sensitive skin.
Open on PubMed ↗

See all studies on PubMed ↗

Scoped PubMed search, not a curated bibliography: the individual PMIDs for this entry have not yet been verified one by one. For that reason it is not used to support a high grade and is awaiting review.

Mechanism

Exfoliate by loosening surface corneocyte bonds like AHAs but more slowly due to larger molecular size; also bind water (humectant) and, for lactobionic acid, chelate metals and scavenge some free radicals.

Safety

Better tolerated than stronger AHAs, so often chosen for sensitive or reactive skin; still increase the value of daily sun protection. Irritation is less common but possible.

Dosage context

Used across a range of concentrations in leave-on and rinse-off products; the appeal is tolerability rather than a high, aggressive percentage. Formulation and pairing matter more than the number.

Examples of application

Chosen as a gentler exfoliant for sensitive or reactive skin.
Used more often than strong AHAs thanks to milder action.
Still paired with daily sunscreen.

From the field

PHAs are the 'sensitive-skin' answer to acids — gentler and hydrating, but with less independent evidence than glycolic or lactic acid. We grade lactobionic/PHAs C and treat them as tolerability picks, not upgrades.

Related molecules

AHA (glycolic / lactic acid)B Panthenol (provitamin B5)C NiacinamideB

Follow this entry

We'll tell you if the grade for PHA (lactobionic acid) changes.

One review a week: new evidence, grade changes and what was updated. No hype, no promotions disguised as news.

How we assign grades → Method