Lactic Acid
A gentle AHA derived from milk that provides chemical exfoliation plus hydration — a unique dual benefit. Lactic acid has a larger molecular size than glycolic acid, so it penetrates more slowly and causes less irritation, making it ideal for sensitive skin and AHA beginners. It also has humectant properties, drawing moisture into the skin as it exfoliates.
Concentration & Usage
Concentrations: 5-12% for daily use. 30-50% for professional peels. Start with 5% every other night. The Ordinary offers 5% (gentle) and 10% (moderate) options. Always use SPF during the day.
Application
Topical (serum, peel, toner). Apply to dry skin at night. Follow with moisturizer.
Shop Lactic Acid
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Mechanism of Action
Lactic acid (90 Da, larger than glycolic acid) exfoliates via the standard AHA mechanism: chelating calcium at corneodesmosomes and promoting desquamation through protease activation. Unlike glycolic acid, lactic acid is a natural component of the skin's natural moisturizing factor (NMF) and functions as a humectant, drawing water into the stratum corneum through hygroscopic binding. It inhibits tyrosinase enzyme activity in melanocytes, providing mild brightening. At higher concentrations (10%+), lactic acid upregulates serine palmitoyltransferase and glucosylceramide synthase in keratinocytes, stimulating ceramide synthesis and improving barrier lipid composition. It also enhances filaggrin proteolysis to NMF components. This dual action—exfoliation plus barrier support—makes it the most moisturizing AHA and clinically useful for dry, sensitive, or barrier-compromised skin.
Ingredient Interactions
There is no benefit to layering two AHAs. Pick one based on your skin type: glycolic for oily/resilient skin, lactic for dry/sensitive skin. Using both is redundant and increases irritation.
Lactic acid is gentler than glycolic but still increases turnover. Separate into AM (lactic acid) and PM (retinol) or alternate nights to avoid irritation.
Though lactic acid is gentle, combining with prescription tretinoin can over-stress the barrier. Alternate or separate routines.
Layering two low-pH products risks irritation. Use vitamin C in the AM and lactic acid at PM, or on different days.
See our full Ingredient Interactions Guide for more combinations and timing strategies.
Regulatory Status
Cosmetic ingredient. Available OTC worldwide. Same FDA AHA guidelines as glycolic acid.
Risks & Safety
Common
Mild stinging, redness — less than glycolic acid at equivalent concentrations. Sun sensitivity.
Serious
None at cosmetic concentrations.
Rare
Over-exfoliation with daily high-concentration use.
Compare Lactic Acid With
Research Papers
10Published: September 12, 2024
AI Summary
PDLLA demonstrates significant benefits in enhancing skin elasticity and firmness, reducing wrinkles, and promoting tissue regeneration and scar remodeling. While potential complications, such as granuloma formation and non-inflammatory nodules, are highlighted, effective monitoring and early intervention strategies are essential.
Published: November 7, 2016
AI Summary
In immunocompetent C57BL/6 mice, tumors with reduced lactic acid production (Ldhalow) developed significantly slower than control tumors and showed increased infiltration with IFN-γ-producing T and NK cells. Database analyses revealed negative correlations between LDHA expression and T cell activation markers in human melanoma patients.
Published: September 24, 2014
AI Summary
Similarly to macrophages in normal tissues and organs, macrophages in tumours (tumour-associated macrophages) perform some key homeostatic functions that allow tumour maintenance and growth. Collectively, these findings identify a mechanism of communication between macrophages and their client cells, including tumour cells.
Published: April 5, 2018
AI Summary
The resultant restoration of facial volume occurs in a controlled, predictable manner and is long lasting. The unique physiochemical and biostimulatory properties of PLLA differentiate it from other available treatments and are the foundation of the unique treatment methodology required for optimal results.
Published: September 15, 2025
AI Summary
Findings confirm that PLLA induces a regenerative cascade marked by M2 macrophage polarization, transforming growth factor beta 1-mediated fibroblast activation, and sustained neocollagenesis, thereby promoting long-term remodeling of the extracellular matrix, improved dermal density, and enhanced skin quality.
Published: May 28, 2024
AI Summary
Recently, lactic acid has been found to induce a posttranslational modification, lactylation, that may offer insight into lactic acid's non-metabolic functions. Notably, the posttranslational modification of proteins by lactylation has emerged as a crucial mechanism by which lactate regulates cellular processes.
Published: March 25, 2025
AI Summary
Here, we provide an evidence-based and expert-led consensus (14 years of off-face treatment experience) on recommendations for appropriate injection protocols for different body sites and evaluation tools when using the biostimulator PLLA-SCA for body aesthetic and rejuvenation procedures.
Published: January 17, 2024
AI Summary
Superficial chemical peels are one of the most popular skin resurfacing procedures in a dermatologists' clinic today due to quick application process, fast recovery, good patient acceptance, and excellent cosmetic results.
Published: March 27, 2024
AI Summary
The concept of "skin boosters" has evolved, marking a shift from traditional uses of hyaluronic acid (HA) fillers primarily for augmenting skin volume to a more diverse application aimed at improving dermal conditions. Restylane Vital and other HA fillers have been repurposed to combat skin aging an
Published: October 28, 2022
AI Summary
Little research is available comparing their effects in terms of new collagen formation post administration. A concise summary of the evidence is provided to assist clinicians in making informed decisions when deciding between the different types of widely available fillers.
Frequently Asked Questions
What is Lactic Acid used for?
A gentle AHA derived from milk that provides chemical exfoliation plus hydration — a unique dual benefit. Lactic acid has a larger molecular size than glycolic acid, so it penetrates more slowly and causes less irritation, making it ideal for sensitive skin and AHA beginners. It also has humectant properties, drawing moisture into the skin as it exfoliates.
What are the side effects of Lactic Acid?
Common: Mild stinging, redness — less than glycolic acid at equivalent concentrations. Sun sensitivity. Serious: None at cosmetic concentrations. Rare: Over-exfoliation with daily high-concentration use.
How is Lactic Acid administered?
Lactic Acid is administered via topical (serum, peel, toner). apply to dry skin at night. follow with moisturizer..
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