去角质
Lactic Acid
INCI: 2-Hydroxypropanoic Acid · Lactate
The Chinese name for Lactic Acid is 乳酸 (pinyin: rǔ suān).
Quick Facts
- Chinese
- 乳酸 (rǔ suān)
- English
- Lactic Acid
- INCI
- Lactic Acid
- Category
- 去角质
- Effective %
- 5% – 12% (typical range in skincare; professional peels use higher concentrations)
- Pregnancy
- Consult doctor
Lactic acid is a gentle, water-soluble AHA that dissolves built-up dead cells for smoother, more refined skin while helping regulate hydration. It's less irritating than glycolic acid at comparable strengths, which makes it the go-to exfoliation option for lower-tolerance skin and a frequent first choice for sensitive types easing into acids.
Key benefits
- Gentle exfoliation: strong evidence that lactic acid dissolves accumulated dead surface cells and smooths rough texture, with less irritation than glycolic acid at the same concentration
- Brightening: clearing surface buildup makes skin look more radiant — the most immediately noticeable effect
- Hydration: its larger molecule penetrates slowly, lingers at the surface, and attracts water; limited evidence that it improves skin water content
- Softening fine lines: regular use promotes epidermal turnover, which can gradually improve fine lines and texture
- Calming reactive skin: some research shows low concentrations can soothe redness, but higher strengths do the opposite — build up gradually
Good for
- Dry and sensitive skin: gentle enough that it rarely causes stinging or worsened dryness
- Dull, rough texture: anyone who wants gentle brightening but worries about stronger acids
- First-time acid users: the best entry-level ingredient for building tolerance
- Maintenance during barrier recovery: very low concentrations can assist mild resurfacing, but still proceed carefully
Use with caution
- Don't layer with strong irritants already in your routine (high-strength retinol or retinal) — irritation stacks
- Pause completely if skin has visible inflammation, redness, or broken areas; resume only after it recovers
- Patch-test first if you're allergic to hydroxy acids or have had a severe reaction before
- If pregnant, check with your doctor before use — lactic acid absorption is low, but rule out any risk
Pairing notes
✓ Pairs well with
✕ Avoid mixing with
Frequently asked
What is Lactic Acid in Chinese?
Lactic acid is 乳酸 (rǔ suān) in Chinese — the same characters in both Simplified and Traditional. It's a gentle, water-soluble AHA that exfoliates dead surface cells while helping skin hold on to moisture.
How often can I safely use lactic acid?
Start at 1-2 times a week; if there's no discomfort after two weeks, work up to 3-4 times. Skip daily use unless the concentration is very low (under 3%). Go by how your skin feels and tolerates it, not a fixed schedule.
Is lactic acid gentler than glycolic acid?
Generally, yes. Lactic acid's larger molecule penetrates more slowly and stays in the upper layers longer, so it's considered gentler than glycolic acid at the same concentration. Sensitive skin should still start low — under 5% — the first time.
Does lactic acid thin the skin?
No. It only removes accumulated dead cells; used correctly over the long term, it actually supports normal skin turnover and a more stable complexion. The caveat is proper use — don't overdo the frequency.
Do I need sunscreen when using lactic acid?
Absolutely. Any AHA increases photosensitivity, and sun exposure can lead to burns and dark spots. SPF 30+ every morning is non-negotiable while you're using it.
Can I use lactic acid with moisturizers?
Yes — recommended, in fact. Applying a hydrating serum or lotion right after lactic acid soothes irritation and locks in moisture. The order: lactic acid → toner → serum/lotion.
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Educational reference only — results vary by person; see a doctor for serious skin issues.