Exfoliating Acids Explained: AHA, BHA, and PHA
Chemical exfoliation has revolutionized skincare routines. With acids like AHA, BHA, and PHA making frequent appearances in toners, serums, and masks, it’s easy to get overwhelmed. But knowing the difference between them—and how to use them—can unlock radiant, clear skin without the damage that harsh scrubs once caused.
This guide compares AHA, BHA, and PHA in detail to help you choose the right exfoliant based on your skin type, concerns, and tolerance.
What Are Exfoliating Acids?
Unlike physical scrubs, exfoliating acids dissolve the “glue” that holds dead skin cells together, allowing them to shed gently. This promotes a smoother texture, clearer pores, and better absorption of your skincare products.
Let’s break down the three major categories:
AHA (Alpha Hydroxy Acids)
Best for: Dry, dull, or sun-damaged skin
AHAs are water-soluble acids derived from natural sources like sugar cane, milk, or fruit. They primarily work on the surface layer of the skin, helping with:
- Brightening dull complexion
- Fading hyperpigmentation and dark spots
- Smoothing fine lines
- Boosting collagen with consistent use
Common AHAs:
- Glycolic acid (strongest, best for experienced users)
- Lactic acid (gentler, hydrating)
- Mandelic acid (ideal for sensitive skin)
- Malic or citric acid (mild supporting acids)
Pro Tip: Start with 5–8% lactic acid 2–3 times per week for a gentle beginning.
BHA (Beta Hydroxy Acids)
Best for: Oily, acne-prone, or congested skin
BHAs are oil-soluble, meaning they can penetrate into the pore lining to break down sebum and unclog blackheads or whiteheads.
Benefits:
- Clears acne and blackheads
- Reduces inflammation and redness
- Controls oil production
- Antibacterial and anti-inflammatory properties
Main BHA:
- Salicylic acid – Ideal for those with breakouts, enlarged pores, or rosacea-prone skin.
Usage Tip: Use a 1–2% salicylic acid product once daily or every other day.
Struggling with redness or post-acne inflammation? Learn more in our article on How to Treat Redness and Irritation.
PHA (Polyhydroxy Acids)
Best for: Sensitive, reactive, or rosacea-prone skin
PHAs are second-generation AHAs with larger molecular sizes, which makes them much gentler and less likely to irritate. They provide mild exfoliation while attracting moisture to the skin.
Benefits:
- Suitable for sensitive or post-procedure skin
- Exfoliates slowly and gently
- Provides antioxidant protection
- Enhances skin hydration
Common PHAs:
- Gluconolactone
- Lactobionic acid
- Galactose
When to use: Great option if AHA or BHA causes stinging or flaking.
Looking for a full soothing skincare routine? Start with our Skincare Routine for Sensitive Skin.
How to Choose the Right Exfoliating Acid
| Skin Type | Recommended Acid | Frequency |
|---|---|---|
| Dry / Dull | AHA (Lactic or Glycolic) | 2–3x/week |
| Oily / Acne-Prone | BHA (Salicylic Acid) | Daily or every other day |
| Sensitive / Rosacea | PHA | 2–4x/week |
Note: You can alternate or combine acids—but do so carefully. For example, use AHA at night and BHA in the morning (with SPF!).
How to Use Exfoliating Acids Safely
- Start slow: Begin with low concentrations and increase as tolerated.
- Apply to clean, dry skin: Usually after cleansing and before serums.
- Avoid layering with other actives: Especially retinoids or vitamin C initially.
- Always wear sunscreen: Acids increase sun sensitivity.
- Listen to your skin: Redness, peeling, or stinging are signs to pause.
Best Products with AHA, BHA, or PHA
AHAs:
- The Ordinary Lactic Acid 5% + HA
- Pixi Glow Tonic (5% Glycolic Acid)
- REN Ready Steady Glow Daily AHA Tonic
BHAs:
- Paula’s Choice 2% BHA Liquid Exfoliant
- COSRX BHA Blackhead Power Liquid
PHAs:
- Neostrata Restore PHA Serum
- The Inkey List PHA Toner
- Glow Recipe Watermelon Glow PHA+BHA Toner
Want anti-aging results too? Check out our Anti-Aging Skincare Tips.
Common Mistakes to Avoid
- Overexfoliating: Using acids daily without breaks can damage your skin barrier.
- Skipping SPF: Chemical exfoliation increases UV sensitivity significantly.
- Mixing everything: Resist the urge to mix acids with retinol or vitamin C until your skin adjusts.
Feeling unsure how to build your weekly schedule? Try integrating acids into your Nighttime Skincare Routine.
Conclusion
AHA, BHA, and PHA are powerful tools for glowing, clear skin—when used correctly. Whether you’re dealing with acne, dullness, or sensitivity, there’s an exfoliant tailored to your needs. The key is patience, smart product choices, and consistency.
Internal Links:
- Skincare Routine for Sensitive Skin
- How to Treat Redness and Irritation
- Anti-Aging Skincare Tips
- Overnight Face Masks
