Lactic acid
Lactic Acid
Lactic acid is a naturally occurring alpha hydroxy acid (AHA) that gently exfoliates dead skin cells while simultaneously moisturizing the skin.
Quick Facts
| INCI Name | Lactic Acid |
|---|---|
| Category | Exfoliant (Alpha Hydroxy Acid) |
| Suitable for | All skin types, especially dry and sensitive skin |
| Typical Concentration | 1-10% in cosmetic products |
Ingredient Scorecard
| Property | Rating |
|---|---|
| Exfoliating effect | ⭐⭐⭐⭐⭐ |
| Moisturizing | ⭐⭐⭐⭐⭐ |
| Skin compatibility | ⭐⭐⭐⭐⭐ |
| Anti-Aging | ⭐⭐⭐⭐⭐ |
| Brightening | ⭐⭐⭐⭐ |
Lactic acid is the mildest of all alpha hydroxy acids and is perfect for sensitive skin that wants to benefit from chemical exfoliation. Unlike other AHAs, it also provides intense hydration and strengthens the skin barrier.
What is Lactic Acid?
Lactic acid belongs to the alpha hydroxy acid (AHA) family and is naturally derived from the fermentation of milk sugar or other sugars. In the Korean cosmetics industry, it is referred to as 젖산 and is a valued ingredient for gentle but effective skin care. Unlike other AHAs such as glycolic acid, lactic acid has a larger molecular structure, which allows for slower and gentler penetration into the skin.
The particular advantage of lactic acid lies in its dual function: while it removes dead skin cells as a chemical exfoliant, it also acts as a natural moisturizing factor. This unique property makes it the ideal choice for people with dry or sensitive skin who want to benefit from an AHA peel without risking irritation.
In modern cosmetic formulations, lactic acid is produced from both natural sources and synthetically. The synthetic variant is identical to the natural form and offers the advantage of consistent quality and purity. Many K-Beauty brands rely on innovative formulations that combine lactic acid with other skin-friendly ingredients.
How Lactic Acid Works on Your Skin
Gentle Chemical Exfoliation
Lactic acid breaks down the bonds between dead skin cells in the outermost layer of the skin and promotes their natural shedding. A study by Bernstein et al. (2001) in the Journal of the American Academy of Dermatology showed that even 12% lactic acid peels produce significant improvements in skin texture. Its gentler effect compared to glycolic acid makes it particularly suitable for sensitive skin types.
Intensive Hydration
As a natural component of the skin's acid mantle, lactic acid acts as a humectant, attracting moisture from the environment. Research by Rawlings and Harding (2004) confirms that lactic acid can increase the skin's water-binding capacity by up to 25%. This moisturizing property distinguishes it from other AHAs and makes it the first choice for dry skin types.
Stimulation of Collagen Production
Regular use of lactic acid stimulates fibroblast activity in the dermis and promotes the formation of new collagen and elastin. A controlled study by Ditre et al. (1996) documented a measurable increase in collagen density after 6 months of use. This leads to improved skin elasticity and reduction of fine lines.
Brightening Effect on Pigment Spots
Lactic acid inhibits tyrosinase activity and reduces melanin production in melanocytes. Studies by Usuki et al. (2003) showed that 5% lactic acid formulations can lighten hyperpigmentation by an average of 30%. The even exfoliation also ensures a more uniform complexion.
Improvement of the Skin Barrier
Unlike other acids, lactic acid strengthens the skin barrier by promoting ceramide synthesis. Research by Babilas et al. (2012) shows that regular use reduces transepidermal water loss (TEWL) by up to 20% and sustainably strengthens the skin barrier.
Who is Lactic Acid Suitable for?
| Skin Type | Suitability | Special Benefits |
|---|---|---|
| Dry Skin | ⭐⭐⭐⭐⭐ | Exfoliation + intensive hydration |
| Sensitive Skin | ⭐⭐⭐⭐⭐ | Mildest AHA option |
| Mature Skin | ⭐⭐⭐⭐⭐ | Anti-aging + collagen boost |
| Normal Skin | ⭐⭐⭐⭐ | Preventive care, skin refinement |
| Oily Skin | ⭐⭐⭐ | Gentle alternative to BHA |
| Acne-Prone Skin | ⭐⭐⭐ | Recommended in combination with BHA |
Integration into your K-Beauty Routine
Time of application: Lactic acid is ideally used in the evening, as AHAs can increase the skin's photosensitivity. In the classic 10-step K-Beauty routine, it belongs in step 4-5, after cleansing and toning, but before essences and serums.
Acclimatization: Start with 1-2 applications per week and gradually increase to daily if your skin tolerates it. Low-concentration products (1-2%) can be used daily, while higher-concentration formulations (5-10%) should only be used 2-3 times a week.
Combination rules: Lactic acid combines well with hyaluronic acid, niacinamide, and ceramides. Avoid simultaneous use with retinol, vitamin C, or other acids on the same evening. Always use a sunscreen with at least SPF 30 the following day.
The best K-Beauty products with lactic acid
For beginners: The Isntree Hyper Acid4 30 Serum for only €3.99 combines four different acids in gentle concentrations and is perfect for starting acid care.
Intensive body care: The SOME BY MI AHA-BHA-PHA 30 Days Miracle Acne Clear Body Cleanser for €20.90 offers a comprehensive acid combination for body acne and keratinization disorders.
Special foot care: The FRUDIA Peach Vinegar Shiny Foot Peeling Socks for €4.99 use lactic acid for intensive foot peels and remove even stubborn calluses.
Targeted Treatment: The Esfolio Foot & Heel Peeling Mask for €8.50 focuses on particularly stressed skin areas and ensures silky soft feet.
Lactic Acid vs. Other Acids
| Acid | Molecule Size | Penetration | Special Feature |
|---|---|---|---|
| Lactic Acid | Large | Slow, gentle | Moisturizing |
| Glycolic Acid | Small | Fast, intense | Strongest AHA |
| Mandelic Acid | Very large | Very gentle | Antibacterial |
| Salicylic Acid (BHA) | Medium | Oil-soluble | Pore-cleansing |
Myths and Facts
Myth: "Lactic acid dries out the skin like other acids."
Fact: Lactic acid is the only AHA that also acts as a humectant and moisturizes the skin instead of drying it out.
Myth: "Lactic acid is less effective than glycolic acid."
Fact: Both acids are equally effective, but differ in their rate of penetration. Lactic acid works more gently and sustainably, especially on sensitive skin.
Myth: "Acid peels are addictive and the skin becomes dependent."
Fact: Acids like lactic acid support the skin's natural renewal process. No dependence develops; the skin retains its natural regenerative capacity.
Frequently Asked Questions about Lactic Acid
Can I use lactic acid daily?
At low concentrations (1-2%), daily use is possible. At higher concentrations, you should start with 2-3 times a week.
Is lactic acid suitable for vegan cosmetics?
Yes, modern lactic acid is mostly produced synthetically or through plant fermentation and is vegan.
How long does it take for the first results to be visible?
First improvements in skin texture are visible after 2-4 weeks; anti-aging effects develop over 3-6 months.
Can I combine lactic acid with retinol?
Do not use simultaneously. Use lactic acid in the evening and retinol on alternate evenings, or lactic acid in the evening and retinol in the morning under sunscreen.
Is lactic acid safe during pregnancy?
AHAs in normal cosmetic concentrations are considered safe, but consult your gynecologist.
What to do in case of overreaction or irritation?
Stop use immediately, rinse with cold water, and apply a soothing cream. Consult a dermatologist if reactions persist.
Do I need to increase sunscreen when using lactic acid?
Yes, AHAs increase photosensitivity. Use at least SPF 30 daily, preferably SPF 50 like the MISSHA All Around Safe Block Aqua Sun Gel SPF50+.
Can I also use lactic acid in the morning?
Generally possible, but due to increased photosensitivity, evening application is safer and more effective.