AHA vs BHA vs PHA: Understanding Korean Skincare Exfoliants

Exfoliating acids show up in K-beauty toners, serums, and even some cleansers. The labels say AHA, BHA, PHA, glycolic, lactic, salicylic, gluconolactone. The marketing often says glow, pores, or “glass.”

This page explains the families, not a ranking of bottles. It will not tell you acids cure acne. It will not invent a percentage that is “right” for everyone. If a product page on this site does not list a concentration, we do not invent one.

Three families, in plain language

AHA (alpha hydroxy acids) — water-soluble acids such as glycolic and lactic acid. They are often discussed for the look of surface texture. They can sting, especially on sensitive skin. American Academy of Dermatology patient education notes that glycolic acid and retinol can irritate, particularly on sensitive skin.

BHA (beta hydroxy acids) — salicylic acid is the BHA most people mean. It is often discussed for congestion-prone or oilier routines. Cleveland Clinic describes salicylic acid as a common BHA. It can dry or irritate. A cleanser that lists BHA is still an acid contact — not automatically a full-face treatment.

PHA (polyhydroxy acids) — such as gluconolactone. They are another hydroxy-acid family used for exfoliation. They are sometimes marketed as “gentler.” Gentle on a label is not a guarantee on your face. Stacking PHA with AHA or BHA is still more than one exfoliating family.

You do not need a dedicated page for every acid name. If a catalog tag says aha or bha, that is family-level information. Unknown INCI stays unknown.

Typical cosmetic purposes — not medical claims

People reach for these acids hoping for smoother-looking texture, a less dull look, or help with the look of congestion. Results vary. An acid is not a diagnosis and not a prescription.

Niacinamide is not an exfoliant. Ceramides are not an exfoliant. Using a hydrating cream next to an acid can make a routine more comfortable. It does not make the acid non-irritating.

Skin type and beginner notes

• Oily or combination T-zone: a BHA cleanser or occasional BHA leave-on is a possible tool, not a requirement. Do not add a second BHA product because the first did not “fix pores.”
• Dry or sensitive: start without a daily acid. If you add one later, use it less often and keep moisturizer.
• Beginners: one exfoliating product. Wait before adding another acid or a retinoid.

Cleveland Clinic’s public acid education suggests introducing one facial acid and waiting before adding another. We treat that as conservative advice, not as a rule that two acids are chemically forbidden.

Why stacking several exfoliants is often unnecessary

A K-beauty routine can accidentally include:

• A cleanser with BHA
• A toner with AHA
• A “glow” serum with more acid

That is three contacts. Our Phase 5 compatibility engine may return use-caution for AHA + BHA on typical answers, and avoid-stacking for sensitive or beginner answers. That means: consider choosing one exfoliating approach. It does not mean “never mix these ingredients” as a law of chemistry.

The same engine may say use-caution for retinol + AHA or retinol + BHA, and separate-routines when you marked sensitive or beginner. Again: irritation awareness, not a toxicology label.

Stronger is not automatically better

A higher percentage, a lower pH, or three acids in one routine can mean more sting — not more glow. If skin is flaking, burning, or staying red, simplify. Sunscreen in the morning still belongs; some acids can increase sun sensitivity.

How this shows up in a routine

After you build a sequence in Find Your Routine, read the compatibility section. If it flags multiple exfoliants, that is editorial guidance. Products are not silently removed.

In our catalog, examples that carry a BHA tag include the COSRX Low pH Good Morning Gel Cleanser and Beauty of Joseon Glow Serum (which also lists niacinamide). Those are facts on the record, not a recommendation to use both in the same routine.

Common mistakes

• Using an acid toner every morning and a retinoid every night in week one.
• Treating PHA as “not an exfoliant” and layering it with AHA.
• Skipping moisturizer because the acid “should dry oil.”

How to simplify

Pick one exfoliating product or none. Keep cleanser, moisturizer, and sunscreen. Add niacinamide or a ceramide cream as support if you want a quieter leave-on — not as a second peel.

Sources

Summarized in our own words from pages we opened:

• Cleveland Clinic — Facial acids
• Cleveland Clinic — Retinol
• AAD — How to test skin care products

Educational content only — not medical advice.