AHA vs BHA vs PHA: Which Exfoliant Is Right for You?

Quick answer: AHAs (glycolic, lactic acid) work on the skin's surface to brighten and smooth texture, BHA (salicylic acid) goes into pores to clear oil and breakouts, and PHA is the gentlest option for sensitive or exfoliant-shy skin that still wants glow without the sting. If you're new to chemical exfoliation, start with PHA or a low-strength AHA and build tolerance from there.

All three are "acids," but they don't behave the same way on skin. Picking the wrong one — or layering them carelessly — is one of the fastest ways to end up with a compromised barrier, redness, and sun sensitivity. Here's how to tell them apart and choose with confidence.

What Are Chemical Exfoliants, Really?

Chemical exfoliants dissolve the "glue" holding dead skin cells together so they shed more evenly than with a scrub. Used correctly, they can fade dullness, soften fine lines, unclog pores, and help serums and moisturizers absorb better. Used incorrectly (too often, too strong, stacked with retinol or other actives), they can strip the moisture barrier and leave skin reactive.

AHA (Alpha Hydroxy Acid): Surface Brightening

AHAs — glycolic acid, lactic acid, mandelic acid — are water-soluble and work mainly on the skin's surface. Glycolic acid has the smallest molecule size, so it penetrates fastest and is the most potent of the group. Lactic acid is gentler and adds hydration as it exfoliates, while mandelic acid is the mildest AHA, often recommended for melanin-rich or sensitive skin.

Best for: Dullness, uneven tone, rough texture, sun damage, and mild fine lines on skin that isn't reactive.

BHA (Beta Hydroxy Acid): Pore-Deep Clearing

Salicylic acid is the main BHA used in skincare. Unlike AHAs, it's oil-soluble, which means it can travel into the pore lining to dissolve excess sebum and dead cell buildup. That makes it the go-to for blackheads, congestion, and breakout-prone skin. It also has mild anti-inflammatory properties, so it tends to calm existing blemishes rather than aggravate them. For a deeper dive into how it works and why it doesn't have to sting, see our guide to BHA 101: salicylic acid without the sting.

Best for: Oily, combination, and acne-prone skin dealing with clogged pores, blackheads, and texture from breakouts.

PHA (Polyhydroxy Acid): The Gentle Entry Point

PHAs — gluconolactone and lactobionic acid are the most common — have larger molecules than AHAs and BHA, so they exfoliate more slowly and stay closer to the surface. This means less irritation, less sun sensitivity, and often an added humectant benefit since PHAs can bind water to the skin. They're a smart starting point for beginners, rosacea-prone skin, or anyone recovering from a compromised barrier.

Best for: Sensitive, reactive, or exfoliant-beginner skin, and anyone layering multiple actives who needs a lower-irritation option.

At a Glance: AHA vs BHA vs PHA

Exfoliant	What It Is	Best For	Strength	Ideal Skin Type
AHA	Water-soluble acid (glycolic, lactic, mandelic)	Dullness, uneven tone, texture, sun damage	Medium–High	Normal, dry, sun-damaged, non-sensitive
BHA	Oil-soluble acid (salicylic)	Clogged pores, blackheads, breakouts	Medium	Oily, combination, acne-prone
PHA	Larger-molecule acid (gluconolactone, lactobionic)	Gentle exfoliation, hydration, beginners	Low	Sensitive, reactive, dry, beginner

How to Choose Based on Your Skin

If your main concern is dullness or tone

Reach for an AHA. Glycolic acid gives the most visible brightening, but if you're new or have some sensitivity, start with a lactic or mandelic formula instead.

If your main concern is breakouts or oiliness

BHA is your match. Because it's oil-soluble, it clears the pore from the inside rather than just polishing the surface.

If your skin is sensitive, dry, or new to actives

Start with PHA. It gives you the smoothing benefits of exfoliation without the redness or peeling that can come with a first-time AHA or BHA.

Prepping and Supporting Your Skin Around Exfoliation

Chemical exfoliants work best on a clean, well-supported canvas. A gentle, low-pH cleanser like the Green Plum Refreshing Cleanser removes buildup without disrupting your barrier before you apply any acid. Browse more gentle options in our cleansers collection.

After exfoliating, skin can be temporarily more reactive, so soothing is key. The Pure Fit Cica Calming True Sheet Mask is a good rescue step on nights when skin feels tight or flushed, and the Cica PDRN Shield Lifting Film Serum helps reinforce the barrier while you build tolerance to a new acid. You'll find more calming and repair formulas in our Cosrx collection and the wider serum treatments collection.

Chemical exfoliation also increases sun sensitivity, no matter which acid you use, so daily SPF isn't optional — the Relief Sun: Rice + Probiotics from Beauty of Joseon is a lightweight, skin-friendly way to cover that step every morning.

Layering Exfoliants With Other Actives

One of the biggest mistakes is stacking an AHA or BHA on the same night as retinol — both increase cell turnover, and combined they can overwhelm the barrier. If you're using the The Retinol 0.1 Cream, save your acid exfoliant for a separate night, or alternate them. For those who want retinol-like benefits with less irritation risk alongside a PHA or mild AHA, the Bakuchiol Plumping Serum is a gentler plant-derived alternative that pairs more comfortably.

For a full walkthrough on the order actives should go on and how to avoid over-layering, check our guide on how to layer skincare to maximize your routine.

A Simple Rule of Thumb

Start low and slow: 2–3 nights a week for any new exfoliant, always followed by hydration and SPF the next morning. If your skin tolerates it well after a few weeks, you can gradually increase frequency. If you notice persistent redness, stinging, or flaking, step back to a gentler option like PHA and rebuild your barrier before trying something stronger again.

FAQ

Can I use AHA, BHA, and PHA all in one routine?

You can, but not necessarily on the same night or in the same product. Many people alternate — for example, BHA a couple nights a week for pores and PHA on other nights for gentle upkeep — rather than stacking all three at once, which raises the risk of irritation.

Which exfoliant is best for beginners?

PHA is generally considered the most beginner-friendly because its larger molecule size means slower, gentler exfoliation with less risk of over-stripping the skin while you're still learning how your skin reacts.

Do I still need sunscreen if I use PHA instead of AHA?

Yes. While PHA is gentler than AHA or BHA, any exfoliation can leave fresher skin more exposed to UV damage, so daily SPF is still essential regardless of which acid you use.

Can I use a chemical exfoliant with retinol?

It's best to avoid using a strong AHA or BHA on the same night as retinol, since both increase cell turnover and can compound irritation. Alternate nights, or consider a gentler retinol alternative like bakuchiol if you want to use both types of actives more often.

How often should I exfoliate with AHA or BHA?

Most people do well starting at 2–3 times per week, then adjusting based on how their skin responds. Signs you're overdoing it include persistent redness, tightness, or a rough, sensitized feeling rather than smoother skin.

Written by Hyerin Park

ENTJ, K-beauty trend hunter, and iced Americano addict. Always researching what's actually trending in Korea, she loves separating hype from products that truly deserve a spot in your routine.