PHAs (Polyhydroxy Acids) and AHAs (Alpha Hydroxy Acids) are both chemical exfoliants used in skincare to remove dead skin cells, but they differ in strength, skin penetration, and how gentle they are.
๐ฌ What are PHAs?
PHAs are a gentler type of exfoliating acid with larger molecules, so they don’t penetrate the skin as deeply. They work mostly on the surface, making them ideal for sensitive or dry skin.
Examples of PHAs:
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Gluconolactone
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Lactobionic acid
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Galactose
Benefits of PHAs:
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Exfoliate dead skin gently
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Hydrate the skin (they're humectants!)
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Strengthen the skin barrier
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Less likely to cause irritation or sun sensitivity
๐ฌ What are AHAs?
AHAs have smaller molecules, allowing them to penetrate deeper into the skin. They are more potent and are best for normal to oily, sun-damaged, or aging skin.
Examples of AHAs:
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Glycolic acid
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Lactic acid
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Mandelic acid
Benefits of AHAs:
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Exfoliate and smooth texture
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Brighten dull skin
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Stimulate collagen
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Help fade dark spots and fine lines
๐ Key Differences:
| Feature | PHAs | AHAs |
|---|---|---|
| Molecule size | Large | Small |
| Skin penetration | Shallow (surface level) | Deeper (within skin layers) |
| Gentleness | Very gentle | Can cause stinging/irritation |
| Best for | Sensitive or dry skin | Normal, oily, or aging skin |
| Hydrating | Yes | Some (like lactic acid) |
| Sun sensitivity | Minimal | Increases sun sensitivity |