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Moumoujus

LAC.

Essential CAS 8049-98-7 / SKIN CONDITIONING

A revered alpha hydroxy acid (AHA), LAC (Lactic Acid) meticulously exfoliates the skin's surface while simultaneously providing critical hydration. This dual-action ingredient works to reveal smoother, brighter skin, diminish imperfections, and strengthen the skin barrier.

Summary

Exfoliant Moisturizer/Humectant Buffering Skin Barrier Support Melanin Dispersion Antibacterial Collagen Production Stimulant

Science

Mechanism of Action

LAC operates as an alpha hydroxy acid (AHA), expertly loosening the desmosomes—intercellular connections—that bind dead skin cells. This action accelerates the natural shedding process and promotes rapid cell renewal, uncovering a fresher, more uniform complexion. Beyond exfoliation, LAC functions as a potent humectant, attracting and retaining moisture within the skin. It boosts the skin's natural moisturizing factor (NMF) and ceramide production, thereby fortifying the skin barrier. LAC also contributes to a reduction in hyperpigmentation by aiding in the dispersal of melanin clusters, offers antibacterial benefits to help balance the skin's microbiome, stimulates collagen synthesis, and possesses anti-inflammatory and immunomodulatory properties. Furthermore, it can enhance the absorption and efficacy of other active ingredients.

Research

Clinical Evidence

High confidence
Effective range 5–12%
Optimal

8%

Key findings

  1. 01 Demonstrated gentle yet effective exfoliation suitable for leave-on formulations.
  2. 02 Initiated observable clinical and epidermal improvements, with no significant dermal changes at this level.
  3. 03 Significantly increased epidermal and dermal firmness and thickness, visibly improving skin smoothness and reducing the appearance of fine lines and wrinkles. Also exhibited superior moisturizing and exfoliating benefits for conditions like Ichthyosis.
  4. 04 Effectively fades discoloration and post-breakout marks by accelerating surface cell shedding and renewal.
  5. 05 Shown to improve visible signs of sun damage, including fine lines, wrinkles, and textural irregularities.
  6. 06 Optimal pH for maximizing skin cell turnover was identified around 3.0, with desquamative effects being highly pH-dependent. The rate of skin turnover was also found to be concentration-dependent at this pH.

Transparency

Dusting Analysis

Not commonly dusted
Min. effective
5%
Red flag below
2.5%

LAC is rarely 'dusted' at sub-efficacious levels due to its well-established role as an active exfoliant and humectant. While concentrations below 2.5% are generally considered safe (especially at higher pH), significant clinical benefits for exfoliation, anti-aging, and skin barrier improvement typically manifest at concentrations of 5% and above. Formulations below 5% may offer some hydrating properties but are unlikely to deliver potent exfoliating or anti-aging results.

The Formula

Formulation

Solubility
Water
Optimal pH 3.5 – 4
0 7 14

Stability

Pure lactic acid is inherently corrosive and unstable, necessitating meticulous formulation and pH buffering. While optimal cell turnover is observed around pH 3.0, a formulation pH of ≥3.5 is recommended by the CIR Expert Panel for consumer cosmetic products containing up to 10% LAC to ensure safety. Concentrations exceeding 18% can lead to self-esterification reactions, forming dimers or polymers. Products with very low pH may exhibit separation and require specific stabilization. Avoid co-formulation with strong oxidizing agents, iodides, and albumin. Violent reactions occur with hydrofluoric acid and nitric acid.

Synergies

  • Peptides
  • Vitamins
  • Antioxidants

Conflicts

  • Oxidizing agents (strong)
  • Iodides
  • Albumin
  • Hydrofluoric acid (violent reaction)
  • Nitric acid (violent reaction)

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
10%
Sensitization risk Moderate

The CIR Expert Panel deems LAC safe for use in cosmetic products at concentrations up to 10% with a final formulation pH of ≥3.5, provided adequate measures are taken to prevent increased sun sensitivity and daily sun protection is advised. For professional salon products, concentrations up to 30% are considered safe for brief, discontinuous use by trained professionals, also with sun protection recommendations. LAC is known to heighten skin's sun sensitivity during use and for up to one week post-discontinuation, increasing sunburn risk. Transient stinging or irritation may occur. Use on children and infants is not recommended. It is also classified as a CLASS 8 Dangerous Good in Australia, requiring special handling.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Verdict

Essential

LAC is an essential, multi-functional AHA that offers scientifically proven benefits for exfoliation, hydration, anti-aging, and hyperpigmentation, making it a cornerstone ingredient for comprehensive skin health.

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