AHA vs BHA vs PHA: The Complete Korean Exfoliation Guide
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If you have ever stood in front of a shelf of Korean toners and serums wondering whether you need AHA, BHA or PHA, you are not alone. These three families of chemical exfoliants are the backbone of smooth, clear, glowy K-beauty skin, but they do different jobs and suit different skin types. This guide explains what each one does, which is right for you, and how to use them without wrecking your skin barrier.
Quick answer
Choose AHA for rough texture, dullness and dark spots; it works on the surface and suits normal, dry and sun-damaged skin. Choose BHA (salicylic acid) if you are oily or acne-prone, because it is oil-soluble and cleans out pores and blackheads. Choose PHA for the gentlest exfoliation if your skin is sensitive or new to acids. Many Korean products blend two or three, so you often do not have to pick just one. Browse them all in our AHA, BHA and PHA exfoliants collection.
Key takeaways
- AHA = surface smoothing, brightening, texture and dark spots.
- BHA = oil-soluble, clears pores, best for oily and acne-prone skin.
- PHA = gentlest, best for sensitive skin and beginners.
- Start 2 to 3 times a week and never over-exfoliate.
- Daily sunscreen is non-negotiable when using acids.
AHA vs BHA vs PHA at a glance
| Acid | Examples | Solubility | Best for | Skin types |
|---|---|---|---|---|
| AHA | Glycolic, lactic, mandelic | Water-soluble | Texture, dullness, dark spots, fine lines | Normal, dry, sun-damaged |
| BHA | Salicylic acid | Oil-soluble | Blackheads, congestion, oil, breakouts | Oily, combination, acne-prone |
| PHA | Gluconolactone, lactobionic acid | Water-soluble (larger molecules) | Gentle exfoliation and hydration | Sensitive, reactive, beginners |
What is AHA?
AHAs (alpha hydroxy acids) such as glycolic, lactic and mandelic acid are water-soluble and work on the surface of the skin, loosening the bonds between dead skin cells so they shed more easily. The result is smoother texture, softer-looking fine lines, more even tone and a brighter glow. AHAs are a great match for normal, dry or sun-damaged skin, and for anyone focused on brightening and even tone. Mandelic and lactic acids have larger molecules, which makes them gentler starting points than glycolic.
What is BHA?
BHA (beta hydroxy acid) almost always means salicylic acid, and its superpower is being oil-soluble. That means it can cut through the oil in your pores and exfoliate from the inside, clearing blackheads, whiteheads and congestion. This makes BHA the top pick for oily and acne-prone skin, and for pore and texture concerns. It also has mild soothing properties, so it can calm the look of angry, congested skin over time.
What is PHA?
PHAs (polyhydroxy acids) like gluconolactone and lactobionic acid are chemically similar to AHAs, but their molecules are larger, so they penetrate more slowly and gently. They exfoliate the surface with far less risk of stinging or irritation, and they even attract a little hydration. That makes PHA the ideal choice for sensitive skin, reactive skin, or anyone easing into exfoliation for the first time.
Which acid should you choose?
- Rough texture, dullness or dark spots — start with an AHA.
- Oily skin, blackheads or breakouts — reach for a BHA.
- Sensitive skin or first-time exfoliator — begin with a gentle PHA.
- Combination skin — an AHA/BHA blend covers both texture and pores.
You do not have to choose only one. Many Korean formulas combine acids for balanced results, and you can use different acids on different nights. Shop the full range in the AHA, BHA and PHA exfoliants collection.
How to use exfoliating acids safely
Acids reward patience and punish overuse. Follow these rules:
- Start slow. Use 2 to 3 times a week in the evening, then build up only if your skin stays comfortable.
- Patch test new acids if your skin is reactive.
- Do not stack. Avoid using acids and retinoids on the same night, and do not layer several strong actives at once.
- Protect your barrier. If skin feels tight, stingy or looks red and flaky, you are over-exfoliating; scale back and focus on barrier repair.
- Wear sunscreen every morning. Acids increase sun sensitivity, so daily Korean sunscreen is essential to protect your skin and your results.
Where acids fit in your routine
Apply acid exfoliants after cleansing and toning, before heavier serums and moisturizer. A simple exfoliating night could look like: cleanse, apply your acid, wait a couple of minutes, then follow with a hydrating serum and a barrier-supporting moisturizer. On nights you exfoliate, skip other strong actives.
Related reading
- Korean Skincare Ingredients Explained
- How to Treat Acne Without Destroying Your Skin Barrier
- How to Repair a Damaged Skin Barrier
Frequently asked questions
What is the difference between AHA, BHA and PHA?
AHA is water-soluble and smooths surface texture and tone; BHA is oil-soluble and cleans out pores, making it best for oily and acne-prone skin; PHA is the gentlest, ideal for sensitive skin and beginners.
Which acid is best for acne and blackheads?
BHA, or salicylic acid, because it is oil-soluble and gets into pores to clear oil, congestion and blackheads. Pair it with soothing, barrier-supporting products to avoid over-drying.
Which acid is best for sensitive skin?
PHA is the gentlest exfoliating acid, so it is the best starting point for sensitive or reactive skin. Lactic and mandelic AHAs are also relatively gentle options.
Can I use AHA and BHA together?
Yes, and many Korean products combine them. Just be careful not to over-exfoliate: if you are using a combined AHA/BHA product, you usually do not need additional acids on the same night.
How often should I exfoliate with acids?
Start 2 to 3 times a week in the evening and build up slowly if your skin tolerates it. More is not better, and over-exfoliating damages your skin barrier.
Do exfoliating acids make you more sensitive to the sun?
Yes. AHAs in particular increase sun sensitivity, so wear a broad-spectrum sunscreen every morning and reapply through the day.
Where does azelaic acid fit in?
Azelaic acid is a gentle multitasker that helps with the look of breakouts, redness and dark spots. It is not an AHA, BHA or PHA, but it pairs well with a gentle exfoliating routine, especially for acne-prone and sensitive skin.