Compare · Ingredients

Glycolic Acid vs Polyhydroxy Acids

Glycolic Acid: Exfoliates rough skin and can modestly improve signs of sun damage. Polyhydroxy Acids: Offers exfoliation through ingredients such as gluconolactone and lactobionic acid.

Research updated 2026-10-25

Four glycolic acid toner and liquid bottles lined up on white, one with its box

Five PHA toner and serum bottles lined up on white with clear liquid swatches beside them

Which one?At a glance What it helps Diagrams Using both Strengths Results Safety How it works Products Questions

Which one is right for you?

Choose Glycolic Acid if…

Choose for rough texture and dullness; start with a mild leave-on formula.

Rough texture or dullness
Mild sun damage
Skin that tolerates acids

Choose Polyhydroxy Acids if…

Choose for mild exfoliation when stronger acids are uncomfortable; tolerance still varies.

Sensitive skin that stings with AHAs
Mild dullness or texture
Gentle exfoliation

Alternatives, not combined

Can you use both?

Both exfoliate. PHAs are much gentler; one is usually enough.

At a glance

● Glycolic Acid

● Polyhydroxy Acids

Type

Alpha hydroxy acid (AHA)

Polyhydroxy acid (PHA) family

What it does

Exfoliates rough skin and can modestly improve signs of sun damage.

Offers exfoliation through ingredients such as gluconolactone and lactobionic acid.

Best for

Dull Skin; Wrinkles and Fine Lines; Sun Spots

Acne; Dull Skin; Sensitive Skin

Studied concentrations

8% leave-on cream and 50% professional peels in separate trials.

14% gluconolactone in an acne trial; newer studies test mixed-acid formulas.

When to use

Start on a few evenings weekly; increase only if comfortable.

Start on a few evenings weekly; increase only if comfortable.

Time to results

Often 8–12 weeks in small cosmetic studies; results may be subtle

Often 8–12 weeks in small cosmetic studies; results may be subtle

Irritation

Stinging, peeling and irritation are possible, particularly on inflamed skin.

Can still sting or cause a rash; sensitive skin does not guarantee tolerance.

Sensitive skin

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Available

Cosmetic or OTC products; some high-strength procedures are separate treatments.

Cosmetic or OTC products; some high-strength procedures are separate treatments.

What it helps

Compare uses by strength of evidence. Evidence level describes confidence in a benefit, not its size.

Evidence level

Glycolic Acid

Polyhydroxy Acids

Moderate evidenceSome supportive research

Dull Skin on light skin.

Dull Skin

Exfoliation can smooth rough texture and improve the look of dull skin.

A relaxed forehead with faint shallow horizontal fine lines.

Wrinkles and Fine Lines

An 8% cream produced modest improvements in photodamaged skin.

—

Limited evidenceEarly or small studies

AI-generated educational illustration of Sun Spots: 1. Sun Spots Header — Light Skin; Lighter skin. Not a clinical photograph.

Sun Spots

A small professional-peel trial found slight lightening of sun spots.

Dull Skin on light skin.

Dull Skin

Small studies of PHA formulas suggest smoother surface texture.

Inflamed acne on light skin. The spots sit in a patch of pink, and the ring of redness around each one is easy to see. A few have a yellow-white head, and the skin between them is dry and flaking.

Acne

One controlled trial found fewer lesions with 14% gluconolactone.

Sensitive Skin on light skin.

Sensitive Skin

Some tested formulas were well tolerated; this is not proof that all PHAs suit reactive skin.

Insufficient evidence

The back of an upper arm on light skin, covered in small rough bumps at every hair opening. Each bump sits in a faint pink ring, so the arm looks evenly speckled and slightly red.

Keratosis Pilaris

The reviewed sources do not establish this ingredient as a treatment for this concern.

Redness and fine superficial vessels across a light-skinned cheek and nose.

Rosacea

The reviewed sources do not establish this ingredient as a treatment for this concern.

Extreme close-up of light skin in an active eczema flare, too close to tell which part of the body it is. Blotchy pink-red inflammation covers the whole frame with no clear edge, with small raised bumps, fine dry scale and a few fresh scratch marks.

Eczema

The reviewed sources do not establish this ingredient as a treatment for this concern.

Ice Pick Scars on light skin.

Ice Pick Scars

The reviewed sources do not establish this ingredient as a treatment for this concern.

The front of one shin on pale skin. The surface is pink with fine white flaking and a few shallow cracks, and the skin around it is even in tone.

Dry Skin

The reviewed sources do not establish this ingredient as a treatment for this concern.

Flat tan patches with soft irregular edges across the forehead and upper cheek of an adult with light skin, the surface completely smooth.

Melasma

The reviewed sources do not establish this ingredient as a treatment for this concern.

Acne scarring on light skin. Small sharply cut pits and broad shallow dips across a cheek, several sitting inside faint flat pink marks, with no active spots.

Acne Scarring

The reviewed sources do not establish this ingredient as a treatment for this concern.

How it works

Glycolic Acid mechanism diagram. Acts at the outer skin: Acidity helps loosen adhesion between dead cells. Promotes surface shedding: Texture changes depend on pH and the formula. — Open full-size diagram
Diagram explanation and sources
Acts at the outer skin: Acidity helps loosen adhesion between dead cells. Promotes surface shedding: Texture changes depend on pH and the formula.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Source 1 · Source 2 · Source 3

Polyhydroxy Acids mechanism diagram. Loosens surface cells: PHAs promote shedding in the outer skin. Helps bind water: Hydroxyl groups contribute to water binding. — Open full-size diagram
Diagram explanation and sources
Loosens surface cells: PHAs promote shedding in the outer skin. Helps bind water: Hydroxyl groups contribute to water binding.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Source 1 · Source 2 · Source 3

Using both in one routine

Built from where each one usually sits in a routine. Introduce one at a time.

Morning

Step 1

Cleanser

Step 2

Polyhydroxy AcidsMorning or night

Step 3

Moisturizer

Step 4

Sunscreen

Night

Step 1

Cleanser

Step 2

Glycolic AcidNight

Step 3

Polyhydroxy AcidsMorning or night

Step 4

Moisturizer

Strengths and forms

Concentrations

Home skincare and office peels use very different glycolic acid strengths. Clinical studies include 8% leave-on cream and professional peels from 20% to 70%.

8%

20–70%

Studied leave-on cream

Studied for sun-damaged skin. Use a finished home product as labeled; this does not establish a universal ideal percentage.

Professional peeling range

Serial office peels have used these strengths for selected concerns. These are controlled procedures, not home-use targets.

Choosing a strength: Choose a home product for your concern and skin tolerance. Ask a qualified clinician whether an office peel is appropriate.

Higher strengths: High-strength peels can cause burns, scars and lasting color changes. Do not copy a study’s peel concentration or timing at home.

Formula matters: Acidity, neutralization, contact time and layers influence peel depth. Two products with the same percentage can act differently.

PHA is a family name, not one ingredient or one standard strength. A clinical acne trial used 14% gluconolactone; that result cannot be transferred directly to lactobionic acid or mixed-PHA products.

14%

Studied gluconolactone lotion

An older controlled acne trial tested this specific formula. It does not establish the best percentage for all PHA skincare.

Choosing a strength: Check which PHA is listed, whether the product stays on or washes off, and whether it also contains other exfoliating acids.

Higher strengths: A PHA product can still irritate, particularly when combined with other acids. A high total-acid percentage is not a validated benefit rating.

Formula matters: The individual acid, acidity and base formula matter. A blended-acid percentage does not reveal the amount of each PHA.

Forms

Toner · Serum · Pads · Peel

Toner · Serum · Cleanser

When you’ll see results

Approximate windows, not promises.

● Glycolic Acid

● Polyhydroxy Acids

First few weeks

First few weeksAssess tolerance and texture; immediate softness can come from the base formula.

First few weeksAssess tolerance and texture; immediate softness can come from the base formula.

4–8 weeks

4–8 weeksSubtle changes may appear in some tested products; evidence varies.

4–8 weeksSubtle changes may appear in some tested products; evidence varies.

8–12 weeks

8–12 weeksCompare photographs in the same lighting and reassess benefit.

8–12 weeksCompare photographs in the same lighting and reassess benefit.

3–6 months

3–6 monthsPhotoaging trials often need several months; expect modest rather than dramatic change.

3–6 monthsPhotoaging trials often need several months; expect modest rather than dramatic change.

6–12 months

6–12 monthsLong-term evidence is limited for many cosmetic actives; continue only if useful.

6–12 monthsLong-term evidence is limited for many cosmetic actives; continue only if useful.

Safety and sensitive skin

Common reactions

Stinging, peeling and irritation are possible, particularly on inflamed skin.

Can still sting or cause a rash; sensitive skin does not guarantee tolerance.

When to stop

Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.

Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.

Sensitive or inflamed skin

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Important limits

Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.

Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.

Pregnancy

Very little is absorbed through the skin and it is commonly used, but this is not a decision to make from a webpage. Ask the doctor managing your pregnancy.

Low-strength leave-on acids are generally considered acceptable; ask the clinician managing your pregnancy.

How it works

In the skin

On the skin. The finished product delivers glycolic acid in a particular vehicle.

Entering skin. Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

Conversion. No activation step is established as necessary for its intended topical role.

Skin response. Loosens adhesion between outer skin cells, promoting exfoliation; concentration, pH and contact time matter.

Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.

On the skin. The finished product delivers polyhydroxy acids in a particular vehicle.

Entering skin. No single molecular mass. The 500 Da guideline cannot be applied to this whole ingredient family or mixture.

Conversion. No activation step is established as necessary for its intended topical role.

Skin response. PHA ingredients promote surface exfoliation and may also bind water; individual acids and formulas differ.

Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.

Getting in

Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

No single molecular mass. The 500 Da guideline cannot be applied to this whole ingredient family or mixture.

Product examples

Glycolic Acid

The INKEY List Glycolic Acid Toner
Paula's Choice 8% AHA Lotion Exfoliant
Paula's Choice RESIST Daily Smoothing Treatment With 5% AHA

Polyhydroxy Acids

Isntree Hyper Acid 4 AHA BHA PHA LHA 30 Serum
NeoStrata Ultra Moisturizing Face Cream
Gold Bond Ultimate Pedi Smooth Foot Cream

Common questions

Glycolic Acid:What should I choose glycolic acid for?

Choose for rough texture and dullness; start with a mild leave-on formula.

Glycolic Acid:How strong is the evidence?

An older 22-week vehicle-controlled trial supports modest photoaging benefits from 8% cream. Results from 50% peels cannot be transferred to everyday serums.

Polyhydroxy Acids:What should I choose polyhydroxy acids for?

Choose for mild exfoliation when stronger acids are uncomfortable; tolerance still varies.

Polyhydroxy Acids:How strong is the evidence?

A 150-person trial tested 14% gluconolactone for acne. Evidence from that molecule or a mixed-acid serum does not establish identical effects for all PHAs.

Sources

Sources and further reading

Dermapedia on YouTube