PHA: Gentle, but Not Risk-Free

Polyhydroxy acid · Gluconolactone · Lactobionic acid

PHAs (polyhydroxy acids) are used in exfoliating formulas; their larger molecules tend to sting less than AHAs for many people. Evidence varies by formula and concern.

Evidence: limited

Label names (INCI): Gluconolactone, Lactobionic Acid, Galactose

Written by the Oliareen editorial teamDermatologist review: pendingLast updated: 6 November 2026How we write

Myth vs fact

Myth: PHA is so gentle it can never irritate.
Fact: A gentle reputation doesn't rule out irritation. If your skin is already red or stinging, don't start any exfoliant.

What it is

Labels list Gluconolactone or Lactobionic Acid. Their molecules are larger than AHAs, so they enter skin more slowly.

What it does

It loosens surface dead cells and also holds water. It has far less research than AHAs, and much of it is small or lab-based.

Often discussed for

This doesn't mean everyone with these needs it.

Concerns

Skin types

How to approach it

It's found in toners, serums and cleansers. You can start a few times a week. Follow the product's directions.

Morning or evening

Morning or evening both work. On sensitive skin, don't layer it with a strong AHA at the same time. Wear sunscreen by day.

If you're new to it

Start one new active at a time and give it at least two to four weeks before adding another. Patch test first: a little on the side of the jaw or behind the ear for a few days. Keep the rest of the routine simple: a gentle cleanser, a moisturiser and sunscreen by day.

General education, not a diagnosis or treatment plan.

Works well with

Examples of common pairings, not guaranteed combinations.

Fits most routines
Hyaluronic acid
Niacinamide

Use carefully with

Stacking several actives raises the risk of irritation. If you're on any prescribed medicine, ask your doctor before adding an active.

Strong AHAs (in the same session, if your skin is sensitive)
Low; still use SPF

Possible reactions

A few seconds of mild tingling or a little dryness can happen at first. Stop if burning doesn't settle, or if a red rash, itching, swelling or peeling keeps getting worse. Swelling of the face, lips or eyes, or trouble breathing, needs urgent medical care.

When to see a doctor

Evidence and timing

Evidence: Evidence: limited
Time to see a change (weeks): 2-8

Evidence comes from studies of specific formulas and strengths. Your product may behave differently.

Questions people ask

PHA or AHA?

AHAs have more evidence; PHAs usually sting less. Nobody strictly needs either. See the comparison on our exfoliation page.

Can sensitive skin use PHA?

Some people can. Patch test first, and don't start while your skin is irritated.

Sources

Bernstein EF et al. Dermatol Surg 2004 (in vitro UV)
Green BA, Yu RJ, Van Scott EJ. Clin Dermatol 2009 (PHA review)
Hunt MJ, Barnetson RS. Australas J Dermatol 1992 (gluconolactone vs BPO, acne)