Glycolic acid gets most of the AHA spotlight, but lactic acid is arguably the more practical choice for a lot of skin types — it exfoliates with a gentler touch and brings a genuine hydration benefit that glycolic acid doesn’t.
What Is Lactic Acid?
Lactic acid is an alpha hydroxy acid (AHA) derived from milk or produced synthetically, with a larger molecular size than glycolic acid. That size difference means it penetrates the skin more slowly and gently, making it a common first-AHA recommendation for sensitive or exfoliation-inexperienced skin.
What Does It Actually Do?
- Exfoliates the skin’s surface — dissolves the bonds between dead skin cells, improving texture and tone over time
- Doubles as a humectant — lactic acid draws moisture into the skin, a benefit most other AHAs don’t share
- Smooths fine lines and rough texture — regular use supports smoother-looking skin with continued exfoliation
- Helps fade surface-level dark spots — supports gradual, even fading of superficial discoloration
Lactic Acid vs Glycolic Acid
Glycolic acid’s smaller molecular size makes it more potent and faster-acting, but also more likely to irritate. Lactic acid trades some of that intensity for tolerability and an added hydration benefit — a reasonable trade for dry, sensitive, or beginner skin, though established exfoliation users may prefer glycolic acid’s stronger effect.
How to Use It
- Start with a low concentration (5-10%) two to three times a week
- Apply to clean, dry skin, and always follow with moisturizer
- Always wear SPF the following morning, as with any exfoliating acid
- Avoid layering with other strong actives (retinol, other acids) on the same night while building tolerance
Who Should Use It
Lactic acid is a strong fit for dry, sensitive, or first-time exfoliation users who want the benefits of chemical exfoliation without the higher irritation risk of glycolic acid. It’s also a reasonable option for those who find glycolic acid too drying.
The Bottom Line
Lactic acid isn’t a weaker version of glycolic acid — it’s a different tool suited to different skin. For dry or reactive skin especially, it delivers real exfoliation with meaningfully less irritation risk.