AHA vs BHA vs PHA: The Complete Korean Exfoliation Guide

Chemical exfoliants are the backbone of Korean skincare routines, but choosing between AHA, BHA, and PHA can be confusing — for consumers and retailers alike. Each acid family works differently, targets different concerns, and suits different skin types. This guide breaks down everything you need to know to recommend the right exfoliant to your customers.

The Three Acid Families Explained

AHA (Alpha Hydroxy Acids)

What they are: Water-soluble acids derived from fruits, milk, and sugar cane.

How they work: AHAs break the bonds between dead skin cells on the skin's surface, revealing fresh, bright skin underneath. They work on the outermost layer of skin (epidermis).

Best for:

• Dry and dehydrated skin (AHAs also attract moisture)
• Dull, uneven skin tone
• Sun damage and age spots
• Fine lines and surface wrinkles
• Rough, textured skin

Common AHAs in Korean skincare:

• Glycolic acid (from sugar cane) — Smallest molecule, strongest exfoliation
• Lactic acid (from milk) — Larger molecule, gentler, also hydrates
• Mandelic acid (from almonds) — Largest molecule, gentlest, safe for darker skin tones
• Tartaric acid (from grapes) — Used in combination with other AHAs
• Citric acid (from citrus) — Mild exfoliant, also adjusts pH

Concentration guide:

• Beginners: 5-8% glycolic or 10% lactic acid
• Intermediate: 10-15% glycolic or 20% mandelic
• Advanced: 20-30% glycolic (professional use)

BHA (Beta Hydroxy Acids)

What they are: Oil-soluble acids, primarily salicylic acid.

How they work: BHAs can dissolve in oil, allowing them to penetrate into pores and dissolve sebum, dead cells, and debris from inside the pore. This is what makes BHA unique — it works below the skin surface.

Best for:

• Oily and acne-prone skin
• Blackheads and whiteheads
• Enlarged pores
• Sebum control
• Inflammatory acne (BHA also has anti-inflammatory properties)

Common BHAs in Korean skincare:

• Salicylic acid — The classic BHA, effective at 0.5-2%
• Betaine salicylate — Korean innovation, gentler than pure salicylic acid
• Willow bark extract — Natural source of salicin (converts to salicylic acid)

Concentration guide:

• Beginners: 0.5% salicylic acid or betaine salicylate
• Intermediate: 1-2% salicylic acid
• Advanced: 2% salicylic acid (maximum OTC concentration in many markets)

PHA (Polyhydroxy Acids)

What they are: Large-molecule acids that exfoliate the outermost skin layer very gently.

How they work: PHAs have a larger molecular structure than AHAs, which means they penetrate skin more slowly and less deeply. This makes them the gentlest chemical exfoliant — suitable for even the most sensitive skin.

Best for:

• Sensitive and reactive skin
• Rosacea-prone skin
• Eczema-prone skin
• Post-procedure skin (after laser, peel, etc.)
• Daily use without risk of over-exfoliation

Common PHAs in Korean skincare:

• Gluconolactone — Exfoliates while attracting moisture, also an antioxidant
• Lactobionic acid — Gentle exfoliation with strong antioxidant properties
• Galactose — Very mild, suitable for the most sensitive skin

Concentration guide:

• PHAs are generally used at 3-15% concentration
• Even at higher concentrations, irritation is minimal

AHA vs BHA vs PHA: Quick Comparison

Feature	AHA	BHA	PHA
Solubility	Water-soluble	Oil-soluble	Water-soluble
Penetration	Surface	Into pores	Surface (gentle)
Best skin type	Dry, dull	Oily, acne	Sensitive
Hydrating	Yes	No	Yes
Anti-inflammatory	Mild	Strong	Mild
Sun sensitivity	Increases	Minimal	Minimal
Frequency	2-3x/week	Daily possible	Daily

Korean Products for Each Acid Type

Best Korean AHA Products

COSRX AHA 7 Whitehead Power Liquid, BY WISHTREND Mandelic Acid 5% Skin Prep Water, SOME BY MI AHA-BHA-PHA 30 Days Miracle Toner

Best Korean BHA Products

COSRX BHA Blackhead Power Liquid, Paula's Choice-inspired Korean dupes, innisfree Bija Trouble Skin

Best Korean PHA Products

COSRX PHA Moisture Renewal Power Cream, NEOGEN Bio-Peel Gauze Peeling (PHA-infused pads), BY WISHTREND Green Tea & Enzyme Powder Wash

Combination Products

Korean brands pioneered the AHA/BHA/PHA combination product — using all three acid types in one formula. The most famous example is SOME BY MI's 30 Days Miracle line, which uses low doses of all three acids for balanced, gentle exfoliation suitable for most skin types.

Retail and Wholesale Recommendations

When building your acid exfoliant assortment:

1. Stock all three types — Cover every skin type and concern
2. Include combination products — These are bestsellers because they simplify decision-making for consumers
3. Offer multiple formats — Toners, pads, serums, and peeling gels appeal to different preferences
4. Educate your customers — Provide clear guidance on which acid suits their skin type

Explore Korean exfoliant brands on knok to compare formulas and connect directly with brand owners for wholesale pricing.

Conclusion

Understanding the differences between AHA, BHA, and PHA is essential for both consumers and retailers. AHAs brighten and smooth surface texture, BHAs clear pores and control oil, and PHAs provide gentle exfoliation for sensitive skin. Korean brands lead in all three categories, offering innovative formulations at competitive wholesale prices. Stock a range covering all three acid types to serve every customer need.