CAS number 50-21-5
INCI name Lactic acid
Lactic acid is a versatile ingredient in personal care products, primarily working as an exfoliant to remove dead skin cells and reveal a softer, smoother surface. It also acts as a humectant, drawing moisture to the skin’s upper layers for lasting hydration. Known for promoting a healthy, youthful complexion, lactic acid is also beneficial for hair, helping to moisturize and condition the shafts for enhanced smoothness and shine. Its chemical formula is C₃H₆O₃.
Purpose
Lactic acid serves multiple purposes in personal care products. It acts as an antimicrobial agent by inhibiting bacterial and fungal growth, helping to preserve formulations and protect the skin. As a humectant, it attracts and retains moisture, keeping the skin hydrated, soft, and plump. Additionally, its skin-conditioning properties enhance texture by gently exfoliating dead cells, promoting cell renewal, and improving overall smoothness for a more youthful, radiant complexion.
Origin
Lactic acid can be naturally produced through the fermentation of sugarcane, corn, or beet. It can also be synthesized through the hydration of acetaldehyde.
| Feature | Description |
| Name | Lactic acid |
| Type | Alpha-Hydroxy Acid (AHA) |
| Source | From the fermentation of carbohydrates |
| PH | 2.5–3.5 |
| Boiling point | 203°C |
| Color | Colorless to pale yellow |
| Odor | Mild, slightly sour odor |
| Physical State | Liquid or solid |
| Concentration | 1-5% |
Gentle Yet Effective Exfoliation
Unlike stronger AHAs like glycolic acid, this has a larger molecular size, which slows down its penetration into the skin. This makes it a gentler exfoliant, effectively removing dead skin cells while minimizing irritation. It promotes cell turnover, revealing fresher, brighter skin without excessive redness or peeling.
Dual-Action Hydration
Lactic acid is not only an exfoliator but also a humectant, meaning it attracts moisture to the skin. It helps replenish hydration while removing dry, flaky skin, making it ideal for balancing exfoliation with hydration. This dual function sets it apart from other AHAs that can sometimes cause excessive dryness.
Naturally Derived & Biodegradable
Lactic acid can be naturally obtained through the fermentation of plant-based sugars, such as those from sugarcane, corn, and beets. This makes it an eco-friendly and biodegradable ingredient, safe for both humans and the environment. It can also be produced synthetically through acetaldehyde hydration, but the natural version is preferred in clean beauty formulations.
Skin Barrier Support
Lactic acid enhances the skin’s natural moisture barrier by increasing ceramide production. Ceramides are lipids essential for retaining moisture and preventing transepidermal water loss (TEWL). This means this not only hydrates the skin but also strengthens its protective barrier, reducing sensitivity and dryness.
Antimicrobial Properties
Lactic acid has inherent antimicrobial properties, making it effective against certain bacteria and fungi. It is commonly used in preservative systems for cosmetics and personal care products to extend shelf life. In skincare, it helps prevent acne and bacterial infections by maintaining a slightly acidic environment that inhibits microbial growth.
Non-Irritating pH Regulator
Lactic acid is often added to formulations as a pH adjuster to maintain the skin’s natural acidity (around pH 4.5-5.5). Unlike some harsh acids that can disrupt the skin’s microbiome, this helps keep the skin’s pH balanced, reducing irritation and promoting a healthier complexion.
Applications of Lactic Acid
Skincare and Personal Care
- Used in chemical peels, serums, toners, and creams for gentle exfoliation and skin renewal.
- Helps improve skin hydration by attracting moisture and strengthening the skin barrier.
- Reduces the appearance of fine lines, wrinkles, and hyperpigmentation by promoting collagen production and cell turnover.
- Used in anti-acne formulations due to its ability to regulate pH and prevent bacterial growth.
- Common in deodorants for its antimicrobial properties.
Haircare
- Conditions and smooths hair shafts, reducing frizz and improving texture.
- Helps regulate scalp pH, preventing excessive dryness or oiliness.
- Used in shampoos, conditioners, and treatments to enhance hair manageability and shine.
