different acids, pha, bha, aha

AHAs, BHAs, PHAs: Which One Is for You? The Ultimate Guide to Chemical Exfoliants

If your skin feels rough, dull, or prone to breakouts, chemical exfoliants might be your new best friend. Unlike physical scrubs, which can irritate the skin, chemical exfoliants work at a deeper level — gently removing dead cells and improving texture, tone, and clarity.

But with so many options — AHAs, BHAs, PHAs — how do you know which one is right for your skin type? In this guide, we’ll break it down scientifically, simply, and with product suggestions included.


What Are Chemical Exfoliants?

Chemical exfoliants dissolve the bonds between dead skin cells, helping them shed naturally. This reveals newer, healthier skin underneath. Unlike scrubs, they don’t rely on friction, making them gentler and more effective in the long run.

The main types are:

AHAs (Alpha-Hydroxy Acids) – Water-soluble and work on the skin’s surface.

BHAs (Beta-Hydroxy Acids) – Oil-soluble and work inside the pores.

PHAs (Polyhydroxy Acids) – Larger molecules that exfoliate gently with added hydration.

Let’s look at each.


Know your Skin Type

Before we delve deeper into this topic,  it is crucial for you to understand your skin type, so you can be sure what ingredient is the best for you.

Knowing whether your skin is oily, dry, sensitive, or combination will help you choose the right acid and avoid unnecessary irritation. If you’re not sure what your skin type is, make sure to read my detailed blog post on how to find your skin type — it’s the foundation of every effective skincare routine.


Alpha-Hydroxy Acids (AHAs)

How They Work

AHAs are water-soluble and work by loosening the bonds between dead skin cells on the outermost layer of the skin. This makes them ideal for dry, dull, or sun-damaged skin.

Types of AHAs

Glycolic Acid: Smallest molecule, penetrates deeply, great for anti-aging.

Lactic Acid: Gentler, hydrates while exfoliating — ideal for dry or sensitive skin.

Mandelic Acid: Slow-penetrating, antibacterial — good for acne-prone or darker skin tones.

Best For

• Dull skin

• Fine lines & wrinkles

• Uneven tone

• Dry, flaky texture

How to Use AHAs

• Start with 1-2 times a week and increase gradually.

• Use at night to avoid sun sensitivity.

• Always follow with SPF 30+ the next morning.

Do NOT Mix With

• Retinoids (unless skin is well-adjusted) (you can read my post on Retinoids to learn everything to know about it)

• Vitamin C (can increase irritation)

• Other acids (unless in a well-formulated product)

Combine With

• Hyaluronic acid (hydration)

• Ceramides (barrier support)

• Niacinamide (soothing)

Recommended Products

• The Ordinary Glycolic Acid 7% Toning Solution

• Paula’s Choice 8% AHA Gel Exfoliant

• Sunday Riley Good Genes Lactic Acid Treatment


Beta-Hydroxy Acids (BHAs)

How They Work

BHAs are oil-soluble and can penetrate deep into the pores. They help dissolve sebum and dead cells inside the follicle, making them perfect for acne-prone or oily skin.

Most Common BHA

Salicylic Acid: Anti-inflammatory, unclogs pores, reduces redness and swelling.

Best For

• Blackheads and whiteheads

• Acne

• Clogged or enlarged pores

• Oily or combination skin

How to Use BHAs

• Apply after cleansing and toning.

• Use 2-3 times a week or daily if your skin tolerates it.

• Avoid using it with strong actives on the same day if you’re new to acids.

Do NOT Mix With

• Retinoids (unless prescribed or skin is adjusted)

• AHAs (can cause over-exfoliation)

Combine With

• Niacinamide (oil control + pore reduction)

• Panthenol or Centella (calming)

• Zinc (for acne control)

Recommended Products

• Paula’s Choice 2% BHA Liquid Exfoliant

• COSRX BHA Blackhead Power Liquid

• La Roche-Posay Effaclar Salicylic Acid Acne Treatment


Polyhydroxy Acids (PHAs)

How They Work

PHAs are the gentlest option. Their larger molecule size means they don’t penetrate as deeply, making them less irritating. They also hydrate the skin and offer antioxidant benefits.

Types of PHAs

• Gluconolactone

• Lactobionic Acid

Best For

• Sensitive skin

• Rosacea-prone skin

• Dry or dehydrated skin

• Post-treatment or barrier-damaged skin

How to Use PHAs

• Can be used daily due to their mildness.

• Great for layering with other ingredients.

• Use as a toner, serum, or moisturizer step.

Do NOT Mix With

• Almost anything is okay — PHAs are gentle and very compatible.

Combine With

• Retinoids (buffered use)

• Vitamin C

• Peptides

• Hydrators

Recommended Products

• The Inkey List PHA Toner

• Neostrata PHA Renewal Lotion

• Glow Recipe Watermelon Glow PHA + BHA Toner


Which Acid for Which Skin Type?

Earlier in this guide, we talked about how understanding your skin type is the first step to building an effective routine. If you haven’t already figured that out, make sure to check out my blog post on how to find your skin type — it’s the foundation for knowing which exfoliant will work best for you. Once you know what your skin needs, choosing the right acid becomes simple.

Skin Type / Concern Best Acid Why
Oily / Acne-Prone Skin BHA (Salicylic Acid) Cleans inside pores, reduces acne
Dry, Dull Skin AHA (Lactic/Glycolic) Smooths texture, boosts glow
Sensitive Skin PHA (Gluconolactone) Gentle exfoliation, adds hydration
Hyperpigmentation / Dark Spots AHA (Glycolic/Mandelic) Fades discoloration
Aging / Fine Lines AHA + PHA combo Targets texture, plumps skin
Blackheads / Clogged Pores BHA Dissolves sebum inside pores

How to Incorporate Acids Into Your Routine

1. Start Slow: Use 1–2x per week and increase as tolerated.

2. Apply After Cleansing: Use acids before moisturizers and oils.

3. Avoid Mixing Too Much: Stick to one acid at a time if you’re new.

4. Hydrate & Protect: Always moisturize after and apply SPF in the morning.

Sample Beginner Routine (with AHA/BHA)

Night:

• Cleanser

• BHA 2% Liquid (for oily skin) or Lactic Acid 5% (for dry skin)

• Niacinamide serum (optional)

• Moisturizer with ceramides

Morning:

• Gentle cleanser

• Hyaluronic acid

• Moisturizer, read my guide, The Best Moistureizers For Sensitive Skin 

• Broad spectrum SPF 30+, read my guide, What Sunscreen Suits you the Best 

Note: Before you use the products always do a Patch Test. You apply a boit of the product on the skin of your forearm and then wait and see if the skins reacts to it.

What Not to Mix

To avoid irritation or damage:

Do NOT Combine Why
AHAs + BHAs Too exfoliating together
Acids + Retinol (if new) Can cause peeling, redness
Acids + Vitamin C (raw form) Can destabilize the pH
Acids + Benzoyl Peroxide Over-drying and irritating

What You Can Mix (With Care)

Safe Mix Effect
AHA/BHA + Hyaluronic Acid Boosts hydration
BHA + Niacinamide Controls oil + soothes
PHA + Retinol Buffers irritation
AHA + Ceramides Strengthens barrier

Always patch test when trying a new combo.


Final Tips for Safe Exfoliation

• Patch test new acids to avoid reactions.

• Don’t exfoliate daily unless the product is gentle.

• SPF is non-negotiable – exfoliated skin is more sun-sensitive.

• Watch for signs of over-exfoliation: redness, sensitivity, flaking.


Conclusion

Chemical exfoliants are powerful tools — but only if used the right way. Whether you’re fighting breakouts, dullness, or sensitivity, there’s an acid that can help. The key is knowing what your skin needs and starting slow.

Still unsure? Here’s a final cheat sheet:

Oily, acne-prone? → Start with BHA

Dry, dull, or uneven tone? → Try AHA

Sensitive or barrier-damaged? → Go with PHA, if you have barrier-damaged skin, read my Ultimate Guide on How to Fix It. 

Always listen to your skin. Simple, science-based skincare will take you far — and your glow will prove it.

I’d love to hear from you! Let me know in the comments which exfoliant you’ve tried or if you’re still not sure which one to pick. Got questions or want me to cover a specific skincare topic next? Just ask! And don’t forget to follow me on Pinterest for skincare tips, routines, and product picks.

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