Complete Guide to Korean Exfoliants: AHA, BHA, PHA Explained
Glowko
Why Chemical Exfoliation is a K-Beauty Essential
If there's one category where K-beauty truly shines, it's chemical exfoliation. Unlike harsh physical scrubs that can damage skin, Korean exfoliants use gentle acids to dissolve dead skin cells, unclog pores, and reveal smoother, brighter skin without irritation.
The three main types - AHA, BHA, and PHA - each work differently and target specific concerns. Understanding which acid (or combination) is right for your skin is key to achieving that coveted glass skin glow.
This comprehensive guide will demystify Korean exfoliants and help you choose the perfect products for your skin type and concerns.
Understanding Chemical Exfoliation: How It Works
Chemical exfoliants use acids to break down the bonds between dead skin cells, allowing them to shed naturally. Unlike physical scrubs that manually buff away surface cells (often too aggressively), chemical exfoliants work gently and can penetrate deeper for more effective results.
Benefits of chemical exfoliation:
- Smoother, more refined skin texture
- Reduced appearance of fine lines and wrinkles
- Unclogged pores and fewer blackheads
- Faded dark spots and hyperpigmentation
- Improved product absorption
- Brighter, more radiant complexion
- Reduced acne and breakouts
AHA (Alpha Hydroxy Acids): Surface Exfoliation & Brightening
What Are AHAs?
AHAs are water-soluble acids derived from fruits and milk. They work on the skin's surface to exfoliate dead cells, improve texture, and boost radiance.
Common AHAs in K-Beauty:
- Glycolic Acid - smallest molecule, deepest penetration, most effective but potentially irritating
- Lactic Acid - gentler than glycolic, also hydrating
- Mandelic Acid - largest molecule, gentlest, good for sensitive skin
- Citric Acid - brightening, antioxidant
Best For:
- Dull skin needing radiance
- Sun damage and age spots
- Fine lines and aging concerns
- Uneven texture
- Normal to dry skin types
Avoid If:
- Very sensitive or compromised skin barrier
- Active rosacea or eczema
- Using strong retinoids (use on alternate nights)
BHA (Beta Hydroxy Acid): Deep Pore Cleansing
What is BHA?
BHA (primarily salicylic acid) is oil-soluble, meaning it can penetrate into pores to dissolve sebum and debris from within. It's the gold standard for pore care and acne treatment.
Salicylic Acid Benefits:
- Penetrates and clears clogged pores
- Dissolves blackheads and whiteheads
- Anti-inflammatory (calms acne)
- Antibacterial properties
- Controls excess oil production
Best For:
- Oily, acne-prone skin
- Blackheads and congested pores
- Large, visible pores
- Combination skin (use on T-zone)
The Isntree Chestnut BHA 0.9% Clear Toner delivers effective BHA exfoliation at a gentle 0.9% concentration, perfect for daily use on oily and acne-prone skin.
Avoid If:
- Aspirin allergy (salicylic acid is related)
- Very dry or dehydrated skin (can be drying)
- Pregnant (consult doctor first)
PHA (Polyhydroxy Acids): The Gentle Giant
What Are PHAs?
PHAs are the newest generation of chemical exfoliants - larger molecules that work more slowly and gently than AHAs. They exfoliate while providing hydration and antioxidant benefits.
Common PHAs:
- Gluconolactone - hydrating, antioxidant
- Lactobionic Acid - moisturizing, chelating
Best For:
- Sensitive skin that can't tolerate AHA/BHA
- Rosacea-prone skin
- Post-procedure skin
- First-time acid users
- Dry skin needing gentle exfoliation
PHA products:
- Biodance Skin Refining Mild PHA Toner - ultra-gentle daily toner
- innisfree Volcanic PHA Pore Refining Toner - PHA + volcanic clay
Multi-Acid Formulas: The K-Beauty Approach
K-beauty often combines AHA, BHA, and PHA in single products for comprehensive exfoliation that addresses multiple concerns while minimizing irritation.
SOME BY MI: The Multi-Acid Specialists
SOME BY MI pioneered the multi-acid trend with their legendary 30 Days Miracle line. The SOME BY MI AHA BHA PHA 30 Days Miracle Toner combines all three acids at gentle concentrations for balanced exfoliation suitable for daily use.
Complete SOME BY MI AHA-BHA-PHA Line:
- AHA-BHA-PHA 30Days Miracle Acne Clear Foam - exfoliating cleanser
- AHA BHA PHA 30 Days Miracle Toner - the cult favorite
- AHA BHA PHA 30 Days Miracle Serum - concentrated treatment
- AHA-BHA-PHA 30Days Miracle Cream - exfoliating moisturizer
- AHA-BHA-PHA Super Miracle Spot All Kill Cream - spot treatment
Advanced Multi-Acid Formulas
The Isntree Hyper Acid 4 (AHA BHA PHA LAH) Serum takes it further with FOUR acids including LAH (Lipohydroxy Acid) for maximum exfoliation and pore refinement.
Gentle Exfoliation: Fruit Acid Toners
For those wanting the benefits of AHAs without strong concentrations, fruit-based toners offer gentle, natural exfoliation.
The Beauty of Joseon Green Plum AHA BHA Toner uses 25% green plum water plus gentle AHA and BHA for a soothing, hydrating exfoliating toner perfect for beginners and sensitive skin.
How to Use Chemical Exfoliants Safely
Starting Out: The Beginner's Protocol
- Start slow: Use 1-2x weekly initially
- Patch test: Always test on a small area first
- Start gentle: Begin with PHA or low-concentration AHA
- Build tolerance: Gradually increase frequency over 4-6 weeks
- Listen to your skin: Reduce frequency if irritation occurs
Application Guidelines
When to apply: Evening routine (acids increase sun sensitivity)
How to apply:
- Cleanse thoroughly
- Apply acid toner/serum to dry skin
- Wait 5-10 minutes (optional but recommended)
- Continue with hydrating products
- Always use SPF 50+ the next morning
Frequency by Acid Type
- PHA: Daily use possible
- Low-concentration AHA/BHA (under 2%): Daily to every other day
- Medium-concentration (2-5%): 2-3x weekly
- High-concentration (5-10%): 1-2x weekly
- Multi-acid formulas: Follow product instructions, typically 2-4x weekly
Complete Exfoliating Routines by Skin Type
For Oily, Acne-Prone Skin
PM Routine (3-4x weekly):
- Double cleanse
- Isntree Chestnut BHA 0.9% Clear Toner
- Wait 10 minutes
- Hydrating essence
- Lightweight moisturizer
Alternative: SOME BY MI AHA BHA PHA 30 Days Miracle Toner for multi-acid approach
For Dull, Aging Skin
PM Routine (2-3x weekly):
- Gentle cleanse
- Beauty of Joseon Green Plum AHA BHA Toner
- Wait 10 minutes
- Nourishing serum
- Rich moisturizer
For Sensitive Skin
PM Routine (2x weekly):
- Gentle cleanse
- Biodance Skin Refining Mild PHA Toner
- Soothing essence
- Barrier-repair cream
For Combination Skin
PM Routine (3x weekly):
- Double cleanse
- SOME BY MI AHA BHA PHA 30 Days Miracle Toner
- Wait 5-10 minutes
- Hydrating serum
- Gel-cream moisturizer
Combining Acids with Other Actives
Safe Combinations:
- Acids + Niacinamide: Wait 10-15 minutes between application
- Acids + Hyaluronic Acid: Perfect pairing - acids prep, HA hydrates
- Acids + Ceramides: Acids exfoliate, ceramides repair
Use with Caution:
- Acids + Vitamin C: Can work together but may irritate; use on alternate days initially
- Acids + Retinol: Both increase cell turnover; use on alternate nights
- Multiple acids: Don't layer different acid products in one routine
Avoid Combining:
- Acids + Benzoyl Peroxide (can deactivate each other)
- Multiple high-strength acids in one routine
- Acids + physical exfoliants (over-exfoliation)
Signs You're Over-Exfoliating
Watch for these warning signs:
- Persistent redness or burning
- Increased sensitivity to products
- Tight, dry, flaky skin
- More breakouts than usual
- Shiny, taut appearance
- Stinging when applying moisturizer
If this happens: Stop all exfoliation immediately, focus on gentle hydration and barrier repair for 1-2 weeks, then restart slowly.
Exfoliating Pads & Peeling Gels
Pre-Soaked Exfoliating Pads
Convenient, mess-free exfoliation:
- SOME BY MI AHA-BHA-PHA 30Days Miracle Truecica Clear Cleansing Pad - dual-sided pads
- MEDIHEAL Chestnut Shell Clear Peeling Pad - gentle peeling pads
Physical-Chemical Hybrid
Beauty of Joseon Apricot Blossom Peeling Gel - gentle gel that pills up to remove dead skin, combining physical and enzymatic exfoliation
Body Exfoliation
Don't forget your body! K-beauty offers excellent body exfoliants:
- SOME BY MI AHA-BHA-PHA 30 Days Miracle Acne Body Cleanser - for body acne
- SOME BY MI AHA-BHA-PHA Miracle Calming Body Lotion - exfoliating body moisturizer
- medicube Red Acne Body Peeling Shot - intensive body treatment
The AHA BHA PHA Collection: Complete Product Guide
Best for Beginners:
Best for Acne-Prone Skin:
Best for Anti-Aging:
Best for Sensitive Skin:
Sunscreen: The Non-Negotiable Rule
Chemical exfoliants increase sun sensitivity. Daily SPF 50+ is mandatory when using acids, even on cloudy days or indoors.
Recommended sunscreens for acid users:
Timeline: When to Expect Results
- 1-2 weeks: Smoother texture, improved radiance
- 4-6 weeks: Reduced congestion, fewer breakouts
- 8-12 weeks: Faded hyperpigmentation, refined pores
- 3-6 months: Significant improvement in texture, tone, and clarity
Consistency is key - chemical exfoliation delivers cumulative benefits over time.
Conclusion: Finding Your Perfect Acid
Chemical exfoliation is one of the most transformative steps you can add to your skincare routine. Whether you choose the pore-clearing power of BHA, the brightening benefits of AHA, the gentle approach of PHA, or the comprehensive coverage of multi-acid formulas, K-beauty offers exceptional options for every skin type and concern.
Start slow, listen to your skin, always wear sunscreen, and watch as your complexion transforms into smoother, brighter, clearer skin.
Ready to start exfoliating? Explore our complete AHA BHA PHA collection and discover the perfect acid for your skin from SOME BY MI, Beauty of Joseon, and Isntree.