If you’re just getting into K-beauty, you’ve probably come across the terms AHA, BHA, and PHA on product labels or skincare blogs. But what do these acids actually do? And are they safe for everyday use?
In Korean skincare, acids are not harsh or intimidating, they’re gentle exfoliants that help you achieve smoother, brighter, and clearer skin. The key is knowing which acid suits your skin type and how to use it properly.
This beginner-friendly guide breaks down the differences between AHA, BHA, and PHA, and how to introduce them into your Korean skincare routine safely and effectively.
What Are Acids in Skincare?
Acids in skincare are chemical exfoliants, meaning they help remove dead skin cells from the surface (or inside the pores) without the need for physical scrubbing. They promote:
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Cell turnover
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Smoother texture
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Brighter complexion
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Less clogged pores
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Fewer breakouts
Korean skincare formulas typically combine these exfoliants with hydrating and soothing ingredients, making them much gentler than Western counterparts.
AHA – Alpha Hydroxy Acid
Best for: Dry, dull, or aging skin
How it works:
AHAs are water-soluble acids that exfoliate the surface of the skin. They’re great for removing dead cells, smoothing fine lines, and brightening the overall tone.
Common types in K-beauty:
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Glycolic acid
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Lactic acid
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Mandelic acid (very gentle and ideal for sensitive skin)
Key benefits:
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Brightens skin tone
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Reduces fine lines
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Improves texture
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Helps fade dark spots
ByKorea Tip: Use AHA at night, followed by a soothing essence or cream. Always wear sunscreen the next day!
BHA – Beta Hydroxy Acid
Best for: Oily, acne-prone, or congested skin
How it works:
BHAs are oil-soluble, which means they can penetrate into your pores and help clear out sebum, blackheads, and debris.
Most popular BHA:
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Salicylic acid
Key benefits:
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Unclogs pores
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Reduces acne and blackheads
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Controls excess oil
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Calms inflammation
ByKorea Tip: Use a low-concentration BHA (0.5–2%) 2–3 times a week to prevent over-drying. Always follow with a hydrating toner or serum.
PHA – Polyhydroxy Acid
Best for: Sensitive skin, beginners, or post-procedure skin
How it works:
PHAs are larger molecules than AHAs, which means they exfoliate more slowly and gently, without penetrating too deeply.
Common types:
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Gluconolactone
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Lactobionic acid
Key benefits:
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Exfoliates without irritation
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Hydrates the skin
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Strengthens the skin barrier
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Provides antioxidant protection
ByKorea Tip: Perfect for daily use or for those who found AHA/BHA too strong. Combine with calming ingredients like centella asiatica or allantoin.
How to Add Acids to Your K-Beauty Routine
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Start slow – Use 1–2 times a week and observe your skin.
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Apply after cleansing – Most exfoliating toners or essences go on clean, dry skin.
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Don’t mix too many actives – Avoid combining acids with retinol or vitamin C in the same routine.
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Hydrate + Protect – Follow with a hydrating serum and always use SPF during the day.
Watch Out For:
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Tingling or redness is normal at first, but burning or peeling means it’s too strong.
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Don’t over-exfoliate — more isn’t better.
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Never skip sunscreen when using acids!
AHAs, BHAs, and PHAs may sound scientific, but they’re some of the most powerful and transformative ingredients in Korean skincare, when used correctly. Whether you’re dealing with dull skin, breakouts, or rough texture, these gentle exfoliants can help you reach your glow goals without compromising your skin barrier.
At ByKorea Beauty, we carefully curate K-beauty products with effective, skin-friendly acids designed to give visible results, with the softness and hydration K-skincare is known for.