AHAs (Alpha Hydroxy Acids), BHAs (Beta Hydroxy Acids), and PHAs (Polyhydroxy Acids) are chemical exfoliants that improve skin texture, tone, and clarity. While all three work to exfoliate the skin and promote cell turnover, they vary in their molecular structure, depth of action, and suitability for different skin types.
Here’s a detailed comparison to help you understand the differences and decide which acid is best for your skin.
What are AHAs (Alpha Hydroxy Acids)?
AHAs are water-soluble acids that exfoliate the surface of the skin, helping to remove dead skin cells and improve brightness and texture.
Key Features of AHAs:
- Purpose: Surface exfoliation for smoother, brighter skin.
- Best For: Normal to dry skin, dullness, uneven skin tone, and fine lines.
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Common Types of AHAs:
- Glycolic Acid: Smallest molecule, penetrates deeply, great for anti-ageing.
- Lactic Acid: Hydrating, gentler, ideal for sensitive skin.
- Mandelic Acid: Large molecule, slow absorption, perfect for very sensitive skin.
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Benefits:
- Smooths fine lines and wrinkles.
- Brightens dull skin.
- Fades hyperpigmentation and dark spots.
What are BHAs (Beta Hydroxy Acids)?
BHAs are oil-soluble acids that penetrate deeper into the pores to exfoliate and remove excess sebum. They’re particularly effective for oily or acne-prone skin.
Key Features of BHAs:
- Purpose: Deep exfoliation inside pores, reduces oil and acne.
- Best For: Oily, acne-prone, or combination skin; clogged pores and blackheads
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Common Type of BHA:
- alicylic Acid: Derived from willow bark, widely used for acne treatment.
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Benefits:
- Unclogs and clears pores.
- Reduces blackheads, whiteheads, and acne.
- Calms redness and inflammation
What are PHAs (Polyhydroxy Acids)?
PHAs are similar to AHAs but have a larger molecular structure, making them gentler on the skin. They exfoliate the surface without penetrating deeply, minimizing irritation
Key Features of PHAs:
- Purpose: Gentle surface exfoliation with added hydration.
- Best For: Sensitive skin, dry skin, or those prone to redness or irritation.
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Common Types of PHAs:
- Gluconolactone: Gentle and hydrating.
- Lactobionic Acid: Helps with hydration and anti-ageing.
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Benefits:
- Exfoliates without irritation.
- Hydrates and strengthens the skin barrier.
- Antioxidant properties protect against environmental damage.
How They Compare
| Feature | AHA | BHA | PHA |
|---|---|---|---|
| Solubility | Water-soluble, works on the skin's surface. | Oil-soluble, penetrates pores. | Water-soluble, works on the skin's surface. |
| Exfoliation Level | Surface-level exfoliation. | Deep pore exfoliation. | Surface-level exfoliation (gentle). |
| Skin Type | Normal to dry skin. | Oily, acne-prone, or combination skin. | Sensitive, dry, or mature skin. |
| Key Benefits | Brightens skin, smooths fine lines, fades pigmentation. | Reduces oil, clears clogged pores, treats acne. | Hydrates, strengthens skin barrier, minimizes irritation. |
| Common Concerns Addressed | Dullness, uneven tone, ageing, pigmentation. | Acne, blackheads, oiliness, inflammation. | Redness, sensitivity, mild dryness. |
| Molecular Size | Small, penetrates well (e.g., glycolic acid). | Small, penetrates deeply into pores. | Large, gentle and slow absorption. |
| Irritation Potential | Moderate to high, depending on concentration. | Moderate, especially for dry or sensitive skin. | Low; least likely to irritate. |
When to Use AHA
Use AHAs if you want to:
- Brighten dull or uneven skin.
- Smooth fine lines and wrinkles.
- Fade dark spots or pigmentation.
- Hydrate dry or normal skin.
How to Use:
- Start with 2-3 times a week at night.
- Always follow with sunscreen during the day, as AHAs increase sun sensitivity.
When to Use BHA
Use BHAs if you want to:
- Treat acne, blackheads, or whiteheads.
- Control excess oil production.
- Unclog and minimize pores.
- Reduce redness or inflammation from breakouts.
How to Use:
- Start with 2-3 times a week.
- Apply after cleansing but before moisturizing.
When to Use PHA
Use PHAs if you want to:
- Exfoliate gently without irritation.
- Hydrate and strengthen your skin barrier.
- Minimize redness or sensitivity.
- Start exfoliating if you’re new to acids.
How to Use:
- Safe to use daily due to its gentleness.
- Ideal for layering with other skincare products.
Can You Use AHA, BHA, and PHA Together?
Yes, but use with caution to avoid over-exfoliation. Here’s how to combine them:
- Alternate Days: Use AHA one day, BHA another, and PHA on days you need gentler care.
- Layering: Apply BHA first (to penetrate pores) and follow with AHA or PHA for surface exfoliation.
Tip: Start with one acid at a time to monitor your skin's tolerance.
Who Should Use Which?
| Skin Concern | Recommended Acid |
|---|---|
| Dullness, Fine Lines | AHA (e.g., glycolic or lactic acid). |
| Oily, Acne-Prone Skin | BHA (e.g., salicylic acid). |
| Sensitive Skin | PHA (e.g., gluconolactone or lactobionic acid). |
| Combination Skin | A mix of AHA and BHA or alternating use. |
Common Mistakes to Avoid
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Over-Exfoliating:
Using acids too frequently can damage the skin barrier and cause irritation. -
Skipping Sunscreen:
Acids make your skin more sensitive to UV damage. -
Mixing Incompatible Ingredients:
Avoid combining acids with strong actives like retinol or vitamin C unless directed by a dermatologist.
Conclusion
- Use AHA for surface exfoliation, brightening, and anti-ageing benefits.
- Opt for BHA to target acne, blackheads, and oily skin.
- Choose PHA if you have sensitive skin or are new to exfoliation.
Each acid has its unique strengths, and incorporating them thoughtfully into your routine can give you healthier, glowing skin.
FAQs About AHA, BHA, and PHA
1. Can I Use Acids Every Day?
PHAs can be used daily due to their gentleness. AHAs and BHAs should be used 2-3 times a week, depending on your skin’s tolerance.
2. Do I Need Sunscreen After Using Acids?
Yes! All acids can increase sun sensitivity, so sunscreen is essential during the day.
3. Which Acid is Best for Beginners?
Start with PHA for gentle exfoliation, or a low-concentration AHA or BHA.
