PHA (Polyhydroxy Acid) Guide 2026: The Gentlest Exfoliant

What PHA is: polyhydroxy acids such as gluconolactone and lactobionic acid exfoliate more gently than AHAs and BHAs. How they compare, strengths and top picks.

Last updated 2026-09-26 · 5 min read · First published 2026-04-13

Heads up: this post has affiliate links. We may earn a small commission if you buy something, at no extra cost to you. We only link to stuff we'd actually tell a friend about. Prices shown are approximate and change often; check the retailer for current pricing.

The short answer

PHAs (polyhydroxy acids) are the gentlest hydroxy-acid exfoliants. The common ones are gluconolactone and lactobionic acid. Their larger molecules work at the surface, so they exfoliate more slowly than glycolic (AHA) or salicylic (BHA) acid but sting less and also hold moisture, which makes them the best fit for sensitive, rosacea-prone or first-time acid users. Typical daily products use about 3-6% gluconolactone.

PHAs are the newest category of hydroxy acids, gentler than AHAs and BHAs. Here’s what they actually do.

What PHAs are

The short answer

PHAs (polyhydroxy acids): gluconolactone, plus the related bionic acids lactobionic and maltobionic acid. Their molecular weight is roughly 2 to 5 times that of glycolic acid, so they penetrate slowly and stay near the surface. Effect: surface-level gentle exfoliation without irritation. Also provides humectant (moisturizing) function. Best-tolerated hydroxy acid category for sensitive skin types.

PHA compounds:

Gluconolactone (most common in skincare)
Lactobionic acid (largest, gentlest)
Maltobionic acid (newer)

PHA properties:

Largest molecular size among hydroxy acids
Gentle surface exfoliation
Moisturizing effect
Low irritation potential

How PHAs compare to AHA/BHA

The short answer

PHA vs AHA: AHAs smaller, penetrate deeper, stronger exfoliation, more irritation potential. PHAs larger, surface-only, gentle, barely any irritation. PHA vs BHA: BHA penetrates pores (oil-soluble), addresses acne specifically. PHAs water-soluble, surface-level, better for reactive skin. PHAs complement rather than replace, many use PHA daily + stronger AHA/BHA weekly.

Comparison:

PHA vs glycolic (AHA): PHA larger, gentler, slower results
PHA vs salicylic (BHA): PHA water-soluble, surface-level; BHA oil-soluble, pore-penetrating
PHA vs mandelic (AHA): both gentle, PHAs slightly gentler still

Top PHA products

Best value

Naturium

Alpha-Arbutin Serum 2%

Under $25

Arbutin + gluconolactone (PHA).

Best for: Pigmentation + gentle exfoliation

"The budget PHA + pigmentation combo."

Check price on Amazon →

Derm favorite

Exuviance

PHA+ Clarifying Toner

Under $50

Multi-PHA daily toner.

Best for: Daily gentle exfoliation

"The dermatology-brand PHA pioneer."

Check price on Amazon →

Best value

The Inkey List

PHA Toner

Under $25

Budget PHA option.

Best for: Affordable PHA entry

"The cheapest legitimate PHA product."

Check price on Amazon →

Best value

Biodance

Skin Refining Mild PHA Toner

Under $25

Gentle PHA exfoliating toner with ceramides.

Best for: Adding a gentle PHA step

"The easy PHA add-on."

Check price on Amazon →

When PHAs win over AHA/BHA

The short answer

PHAs better than AHA/BHA for: rosacea-prone skin, sensitive/reactive skin, post-procedure maintenance, pregnancy (gentle enough), first-time acid users, those who react to glycolic/salicylic. AHA/BHA still better for: thick skin, stubborn acne, severe texture, pigmentation work where penetration matters.

PHAs win for:

Rosacea-prone skin
Sensitive/reactive skin
Post-procedure maintenance
Pregnancy (gentle enough)
First-time acid users
Glycolic-intolerant

AHA/BHA still better for:

Thick skin
Stubborn acne
Aggressive exfoliation needs
Deep pigmentation

Typical concentrations

The short answer

PHA concentrations: Daily use: 3-6% gluconolactone. Stronger (weekly): 7-10% PHA products. In-office (medium): 10-20% PHA peels. PHAs are generally tolerated at higher concentrations than AHAs. Useful for sensitive skin where glycolic is overwhelming.

Concentration guide:

Daily: 3-6% gluconolactone
Weekly stronger: 7-10% PHA
Professional: 10-20% PHA peels

Routine integration

Daily: PHA toner or serum
Combine with: vitamin C, peptides, hyaluronic acid
Space from: retinol (use alternate nights)
During pregnancy: generally safe, check with OB

Premium Beauty

TFC8 tech. The one celebrities keep talking about.

Buy on Amazon →

PHA vs AHA vs BHA at a glance

	PHA	AHA (glycolic, lactic)	BHA (salicylic)
Molecule size	Largest	Smallest	Small, oil-soluble
Works where	Skin surface	Surface and upper layers	Inside pores
Irritation	Lowest	Moderate to high	Moderate
Also hydrates	Yes	Lactic somewhat	No
Best for	Sensitive, rosacea-prone, first acid	Texture, dullness, sun damage	Blackheads, oily and acne-prone skin

Sources

Grimes PE, Green BA, Wildnauer RH, Edison BL. The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis, 2004.
Green BA, Yu RJ, Van Scott EJ. Clinical and cosmeceutical uses of hydroxyacids. Clinics in Dermatology, 2009.

Researched, not medical advice. For stronger options, see the best AHA exfoliants and mandelic acid vs salicylic acid.

Frequently asked

What is PHA in skincare? +

PHA stands for polyhydroxy acid, a family of gentle chemical exfoliants that includes gluconolactone and the related lactobionic acid. They loosen dead skin cells at the surface like AHAs do, but their larger molecules absorb more slowly, so they cause less stinging and also act as humectants that hold water in the skin.

What are examples of PHAs? +

Gluconolactone is the most common PHA in skincare. Lactobionic acid and maltobionic acid are closely related bionic acids used the same way. On an ingredient list, look for any of those three names.

PHA vs BHA for pores? +

BHA is better for pore-level congestion (oil-soluble, penetrates pores). PHA is better for surface-level dullness and reactive skin.

Can I use PHA daily? +

Yes. PHAs are gentle enough for daily use even in sensitive skin. Start every other day for 2 weeks, then daily if tolerated.

Does PHA replace glycolic acid? +

Not for all uses. PHA is gentler alternative for sensitive skin; glycolic is stronger for thick skin. Different tools for different needs.

Is PHA pregnancy safe? +

Generally yes. Gentler than AHA/BHA. Not fully studied in pregnancy but lower concentration + gentle action makes many OBs approve.

Which PHA is best? +

Gluconolactone is most researched and widely available. Lactobionic acid is slightly gentler still. Either works.

Keep reading

All articles →

tretinoin

Is SkinCeuticals Triple Lipid Restore 2:4:2 Worth It? Honest Review

SkinCeuticals Triple Lipid Restore 2:4:2 is the barrier cream derms recommend for mature skin. How to layer it with tretinoin, how long a jar lasts, and who should skip it.

Updated 2026-10-15 · 7 min read Read →

tretinoin

What Is Rosehip Oil? The Complete Skincare Guide

Rosehip oil is a vitamin A-containing facial oil, not a standardized retinoid. Here is what it can and cannot do, and how it compares with retinol and tretinoin.

Updated 2026-10-15 · 4 min read Read →

tretinoin

Encapsulated Retinol vs Regular Retinol: Why Encapsulation Wins

Encapsulated retinol is the modern delivery system that makes retinol gentler + more stable. Here's the complete guide and best products.

Updated 2026-10-07 · 5 min read Read →

Premium Beauty

TFC8 tech. The one celebrities keep talking about.

Buy on Amazon →