Lactic Acid

Lactic acid is an AHA (alpha hydroxy acid) used in skincare for exfoliation, brightening, hydration, and pH adjustment. It is gentler than glycolic acid and naturally found in fermented ingredients.

INCI: Lactic Acid

Typical Strength: 80% liquid

Must be diluted before use in final formulas

Key Benefits for Skin

✔ 1. Gentle Exfoliation: Removes dead skin cells → brighter, smoother skin.

✔ 2. Hydration: Has natural humectant properties.

✔ 3. Brightening: Reduces dullness, uneven tone, and rough texture.

✔ 4. Helps unclog pores: Good for acne-prone and textured skin.

✔ 5. Promotes skin renewal: Improves skin softness and glow.

Application

• Toners
• Exfoliating serums
• Peels
• Body lotions
• Foot creams
• Cleansers (low %)

Usage Rates

1. Mild Daily Use (Safe for leave-on): 2–5% lactic acid

2. Treatment Strength: 5–10% (still fairly gentle compared to glycolic)

3. Body Products: 10–12% (treats rough skin, keratosis pilaris)

4. Peels (Professional only): 20–30% Not recommended for home/public, and not for DIY.

⚠ IMPORTANT pH RULE

To work as an exfoliant:

• The final pH MUST be 3.5–4.0
• If the pH is higher than 4.5 → exfoliation becomes weak.
• If the pH is lower than 3 → irritation risk increases.

How to Formulate With Lactic Acid

1. Add during cool-down: Below 40°C to avoid degradation.

2. Always measure pH: Essential in all AHA products.

3. Add slowly: Lactic acid drops pH VERY fast.

4. Combine with humectants

Works well with:

• Glycerin
• Sodium lactate
• Hyaluronic acid
• Panthenol

5. Avoid with strong exfoliants

Don’t mix with strong:

• Vitamin C (pure ascorbic acid)
• Retinol
• Other AHAs/BHAs in high %
• unless you’re making an advanced formulation.

Example: Gentle Lactic Acid Toner (100 g)

Water Phase

• Distilled water – 82%
• Glycerin – 5%
• Sodium lactate – 2%
• Panthenol – 1%

Actives

• Lactic acid (90%) – 5%
  (final active acid ≈ 4.5%)

Others

• Preservative – 0.5%
• Fragrance – optional
• Adjust pH to 3.8–4.0