What Is Glycolic Acid? The Strongest AHA Explained
Glycolic acid is the smallest AHA molecule, meaning deepest penetration. Here's what it does, who should use it, and the best products.
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Glycolic acid is the smallest alpha hydroxy acid molecule, derived from sugar cane. Its small size lets it penetrate deeper than other AHAs, delivering stronger exfoliation. Effective at 5-10% for home use. Higher than 10% is for chemical peels, usually in-office.
The strongest AHA you can buy OTC. Here’s when to use it.
How glycolic acid works
Glycolic acid dissolves the bonds between dead skin cells on the surface. Unlike mechanical exfoliation (scrubs), it works uniformly without micro-tears. Penetrates deeper than lactic acid due to smaller molecular size. Effective at 5-10% daily; higher strengths need spacing.
Glycolic vs other AHAs:
- Glycolic: smallest molecule, deepest penetration, strongest
- Lactic: larger, gentler, mildly hydrating
- Mandelic: largest AHA, gentlest, good for sensitive skin
- Citric: surface-only, mild
Top glycolic products
The Ordinary
Glycolic Acid 7% Toner
Daily-use 7% glycolic toner at $10.
Best for: Daily exfoliation for oily/normal skin
Timeless
20% Vitamin C + E Ferulic Serum
20% L-ascorbic acid with vitamin E and ferulic acid. A no-frills brightening antioxidant serum.
Best for: Mature skin, anti-aging, advanced exfoliation
The original cult glycolic toner.
Best for: Gentle daily glycolic
When NOT to use glycolic
Skip glycolic if: using retinoid same night (over-exfoliation), severe rosacea (triggers flares), post-procedure healing, or during active sunburn. Always wear SPF 30+ next day — glycolic increases photosensitivity.
Frequently asked
Can I use glycolic daily? +
At 5-7% yes. At 10%+ space it 2-3x weekly.
Glycolic vs retinol — which first? +
Retinol first if anti-aging is primary goal. Glycolic first for texture + dullness.
Keep reading
All articles →guides
Glycolic vs Lactic Acid 2026: Which Exfoliant Is Right for Your Skin?
Glycolic vs lactic acid head-to-head: glycolic wins for anti-aging and texture; lactic wins for sensitive skin, dryness, and gentle hyperpigmentation. Full breakdown + how to choose by skin type.
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Best AHA Exfoliant: 5 Picks for Smoother Skin
AHA exfoliants smooth texture, fade pigment, and prep skin. Here are the 5 best — from $8 budget to $138 pharma-grade.
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What Is Lactic Acid? The Gentle AHA for Sensitive Skin
Lactic acid is the gentler AHA alternative to glycolic. Here's how it works, who should use it, and the best products.
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