AHA vs. BHA vs. PHA: Which Exfoliating Acid Does Your Skin Need?
AHA, BHA and PHA are exfoliating acids used to smooth texture, pores and dullness. AHAs such as glycolic or lactic acid work on the surface and suit dull or uneven-looking skin. BHAs, usually salicylic acid, are oil-soluble and often used for clogged pores. PHAs such as gluconolactone are larger, gentler surface exfoliants often considered for sensitive skin.
All three belong to the broader world of hydroxy acids, but they differ in structure, solubility and the concerns they are commonly used for. As a licensed esthetician, I would rather you choose with a little precision than collect every acid in the cabinet.
| AHA | BHA | PHA | |
|---|---|---|---|
| Stands for | Alpha-hydroxy acid | Beta-hydroxy acid | Polyhydroxy acid |
| Common examples | Glycolic acid, lactic acid | Salicylic acid | Gluconolactone, lactobionic acid |
| How it behaves | Water-soluble; works on the surface | Oil-soluble; often used for pores | Larger molecule; gentler surface exfoliation |
| Often chosen for | Dullness, rough texture, uneven-looking tone | Clogged pores, oiliness, breakouts | Sensitive or easily irritated skin that still wants a polish |
The best acid is not the strongest one. It is the one that addresses your concern without keeping your skin irritated.
What are exfoliating acids?
Chemical exfoliants use acids to loosen the bonds involved in surface-cell buildup rather than physically scrubbing skin away.
Hydroxy acids are used in cosmetic and dermatologic formulations for concerns including texture, acne and pigmentation. A scientific review covers alpha-hydroxy acids, beta-hydroxy acids and polyhydroxy acids as distinct groups with different cosmetic applications. Read the review on PubMed.
What is AHA?
AHA stands for alpha-hydroxy acid. Common examples include glycolic acid and lactic acid.
AHAs are water-soluble and are especially associated with surface exfoliation. They are commonly used for dullness, rough texture and visible signs of photoaging.
A 2024 review of AHAs discusses their use for texture, pigmentation, acne and photoaging while also emphasizing that concentration and formulation influence both effectiveness and irritation risk. See the review.
What is BHA?
In skincare, BHA usually refers to salicylic acid.
Salicylic acid is oil-soluble, which makes it particularly useful in formulas aimed at oily skin, clogged pores and breakouts. That does not mean dry skin can never use BHA, but the reason for choosing it should be clear.
What is PHA?
PHA stands for polyhydroxy acid. Gluconolactone is a common example.
PHAs have larger molecular structures than traditional AHAs and are often used in products positioned for gentler surface exfoliation. They can be appealing when you want some exfoliating effect without making a strong glycolic formula your first move.
AHA vs. BHA: which is better?
Neither. They solve somewhat different problems.
If rough surface texture, dullness or uneven-looking tone is the main concern, an AHA may make sense. If clogged pores and oiliness are the bigger issue, a BHA may be more relevant.
Some formulas combine them, which can be useful, but combining acids does not automatically make a product superior.
Where does PHA fit?
PHA can be a useful option for someone who wants surface exfoliation but prefers a gentler approach. Still, “PHA” is not a guarantee that a product cannot irritate you. Concentration, pH, frequency and the rest of the formula matter.
PHA vs. AHA: What Is the Difference?
PHA vs. AHA comes down to strength and feel. AHAs such as glycolic and lactic acid are smaller molecules associated with more noticeable surface exfoliation for dullness and rough texture. PHAs such as gluconolactone are larger molecules often formulated for gentler exfoliation, which is why they appeal to sensitive or easily irritated skin.
If your skin tolerates acids well and texture is the main goal, an AHA may make sense. If acids have left you stinging or tight before, a PHA formula is a softer place to begin. Either way, patch test and follow the directions.
Glycolic Acid vs. PHA
Glycolic acid is the smallest AHA, which is part of why it tends to feel more noticeable in a formula and can be more likely to sting at higher strengths. PHA is generally positioned as the softer option. Choose glycolic acid for stubborn roughness on resilient skin; choose PHA when comfort and consistency matter more than speed.
Can you use AHA, BHA and PHA together?
You can use a finished product formulated with multiple hydroxy acids. That is different from independently layering an AHA toner, a BHA serum and a PHA treatment because more sounds better. When acids are already combined in one formula, treat that product as a single exfoliating step, then follow with moisturizer.
After any acid step, I like a comfortable cream such as NOWIAM Multi Care Capsule Lab Cream so skin is sealed, not left tight and shiny. See NOWIAM for that comfort texture.
How often should you exfoliate?
There is no universal schedule. Product strength, your skin type, other active ingredients and your tolerance all matter.
If you are new to acids, start less frequently and observe your skin. Daily use is not a badge of honor.
If your face begins to sting, peel or react to basic moisturizer, reduce the active load and read our guide to repairing a damaged skin barrier.
Can you use acids with retinol?
Some experienced users can use both within an overall routine, but stacking them indiscriminately can increase irritation.
If you are introducing a retinoid, I generally prefer not to simultaneously increase exfoliation. Give each active enough space that you can tell what your skin tolerates.
Can mature skin use exfoliating acids?
Yes, but mature skin often becomes drier, so exfoliation should support the routine rather than dominate it.
An AHA may help with dull surface texture, but if skin is already dry and reactive, barrier support may deserve priority.
Read Korean Skincare for Mature Skin for a more complete routine.
Do acids make skin more sensitive to the sun?
Some AHAs have been associated with increased sensitivity to UV exposure, which is another reason sunscreen belongs in any routine using exfoliating acids. Reviews of hydroxy acids specifically discuss their interaction with sun-exposed skin. See the research overview.
Use broad-spectrum SPF 30 or higher every morning and follow the directions on your specific exfoliating product.
How to choose between AHA, BHA and PHA
Choose AHA when surface dullness and rough texture are the main targets.
Choose BHA when clogged pores and oiliness are more important.
Consider PHA when you want a gentler style of surface exfoliation.
Choose a balanced multi-acid formula when it is thoughtfully formulated and suits your skin rather than because three acids sound more powerful than one.
The Dew Standard Take
Exfoliation is one of the areas where restraint improves results.
The goal is smooth, clear-looking skin, not proof that you can tolerate the strongest acid routine on the internet. Choose the acid according to the problem, then use the minimum frequency that gets the job done comfortably.
If you want a hydrating cream after exfoliation, start with NOWIAM Multi Care Capsule Lab Cream.
Frequently Asked Questions
What is the difference between AHA, BHA and PHA?
AHAs are water-soluble surface exfoliants, BHAs are oil-soluble and often used for pores, and PHAs are larger, usually gentler surface exfoliants. The comparison table at the top of this guide is the short version.
Can I use AHA and BHA together?
Yes, if they are already combined in one well-formulated product, or if you alternate them on different nights. Layering several strong acids in one routine is a common way to irritate skin.
Is AHA or BHA better for dark spots?
AHAs are often used for surface texture and uneven tone, while BHA is especially useful for clogged pores. Pigmentation can have different causes, so sunscreen and other targeted ingredients may also be important. See Korean skincare for dark spots.
Is PHA better for sensitive skin?
PHA is often formulated as a gentler exfoliating option, but sensitive skin can still react. Start cautiously and evaluate the whole formula.
Is PHA gentler than AHA?
PHA is often formulated as the gentler option because of its larger molecule, but concentration, pH and the rest of the formula still decide how it feels on your skin.
Can I use glycolic acid and PHA together?
Some finished products combine them. Avoid layering a separate glycolic product and a PHA product on the same night unless your skin clearly tolerates it.
How often should I use AHA, BHA or PHA?
There is no universal schedule. If you are new to acids, start a few times a week, then increase only if skin stays comfortable. Follow the product directions.
Can I exfoliate every day?
Some products are formulated for frequent use, but many people do not need daily exfoliation. Follow product directions and reduce frequency if skin becomes irritated.
Can I use acids with retinol?
Some experienced users can use both in an overall routine, but stacking them in the same session can increase irritation. Introduce one change at a time.
Should I use exfoliating acids in the morning or at night?
Many people prefer them at night. Follow the individual product directions and use sunscreen consistently during the day.
Educational content only. Persistent acne, pigmentation or irritation should be evaluated by a dermatologist.
Related reading: building a balanced routine around exfoliation.
THE DEW STANDARD
