Lactic Acid

What is the summary?

• Lactic acid is an Alpha Hydroxy Acid
• It can be used as a clinical peel or skin care ingredient 
• Lactic acid’s role is to exfoliate the skin
• Exfoliation improves pigmentation & enhances skin whitening
• Exfoliation also potentiates the absorption of other creams & actives
• Lactic acid is frequently used to treat melasma pigment & post inflammatory hyperpigmentation

What is lactic acid?

Lactic acid is an alpha hydroxy acid (AHA) derived from fermented milk or produced synthetically. In dermatology and skin care, lactic acid is used primarily as an exfoliant, humectant, and pH regulator & is frequently combined with other pigment correctors such as tranexamic, ascorbic & kojic acids.

Why should you use it for pigmentation & melasma?

AHAs such as glycolic & lactic exfoliate the dead skin cells. This reduces pigment in the upper layers of skin. 

Both these actions result in better light transmission, thus improving the luminosity of skin. Lactic acid can also potentiate the absorption of pigment correctors, hence why it is frequently mixed with arbutin, kojic acid, hydroquinone, & ascorbic acid.

How good is it for melasma pigment?

As a stand alone ingredient (lactic acid by itself), it is rat sh*t. Combined with other ingredients such as glycolic acid, hydroquinone, arbutin, Kojic acid, ascorbic acid, niacinamide & other pigment correctors, lactic acid has its place in rotational therapy. 

Bottom line: best used with pico laser, novel peels & medical therapy to maintain results.

How long does it take to work?

Results are seen at about 2 to 3 weeks, however it may take up to 6-10 weeks for maximal effects. Lactic acid is best combined with other skin care actives that suppress pigment production. 

Lactic Acid in Skin Care: Scientific Overview

Lactic acid is an alpha hydroxy acid (AHA) derived from fermented milk or produced synthetically. It is a water-soluble compound with the chemical formula C3H6O3C3​H6​O3​. In dermatology and skin care, lactic acid is used primarily as an exfoliant, humectant, and pH regulator.

How does lactic acid work?

Lactic acid helps with pigmentation via- 

1. Exfoliation:
   • Lactic acid loosens the bonds between dead skin cells (corneocytes) in the stratum corneum, promoting cellular turnover. This improves skin texture and tone by removing dull or hyperpigmented layers of the epidermis. This is the primary role of lactic acid in the treatment of melasma & post inflammatory hyperpigmentation.
2. Hydration:
   • Lactic acid acts as a humectant, attracting water molecules to the skin, improving its moisture retention, and enhancing the skin barrier. Hydration helps improve skin glow & hence can be useful for skin whitening.
3. Stimulation of Collagen Production:
   • Regular use at appropriate concentrations can stimulate fibroblasts in the dermis, encouraging collagen synthesis and improving elasticity and fine lines. This can help late onset melasma by remodeling the deeper dermal layers of skin.

How often should I use lactic acid?

Lactic acid can be used via 3 ways. 

1. Nightly. Our least favorite in our opinion. The disadvantage of this method is that the concentrations are neither low nor high. 
2. With other skin care products (premixed), with other acids including ascorbic & glycolic acid. 
3. In a pulsed or skin cycling manner, once every 7 -14 days. The concentration of pulsed lactic acid serum ranges from 12 to 18% in a moderately low pH formula. We often use this method during your maintenance phase of melasma treatment. AHA Elucent is our preferred brand as it combines glycolic acid & lactic acid in the one product. 

What is the difference between lactic acid peels & lactic acid serums?

In office lactic acid peels have a lower pH with higher bioavailability. They range from 20 to 70%. These peels require neutralization. 

Home use lactic acid serums have lower concentrations, typically up to 12 percent. They don’t require washing off, as compared to peel formulations. 

Which is better- glycolic acid or lactic acid?

Both glycolic acid and lactic acid are effective for treating pigmentation, including melasma, but their suitability depends on individual skin types and the severity of the pigmentation.

Glycolic acid is a smaller molecule in the alpha hydroxy acid (AHA) family, glycolic acid penetrates deeper into the skin layers. It effectively exfoliates, increases cell turnover, and reduces pigmentation.

Ideal for individuals with thicker or more resilient skin. It targets deeper pigmentation and is often used in chemical peels.

Drawbacks- Can cause irritation, redness, or peeling in sensitive skin types due to its high penetration depth.

Lactic Acid is a larger AHA molecule derived from milk, lactic acid is gentler on the skin. It exfoliates while also providing hydration, making it suitable for dry or sensitive skin. It may not be as effective for deeper pigmentation compared to glycolic acid.

Studies have shown that both acids significantly reduce hyperpigmentation, but glycolic acid may offer more pronounced results. Lactic acid, however, is better tolerated in individuals prone to irritation.

Conclusion: Glycolic acid is better for severe pigmentation, thicker skin types, & individuals seeking aggressive treatment. Lactic acid is best for sensitive skin, mild pigmentation, or those needing hydration alongside pigmentation reduction.

Does lactic acid have any side effects?

Side effects are directly proportional to concentration & indirectly proportional to the IQ of the user. 

• Sensitivity: Can cause irritation or redness, especially in individuals with sensitive skin. Higher concentrations or combination with other acids increases skin sensitivity.
• Sun Sensitivity: Increases photosensitivity; sunscreen use is essential.
• Allergic reactions: are exceedingly rare, most cases are irritant not allergic.

What is an example of a skin care routine using lactic acid for treating melasma?

A simple melasma skincare routine is as follows: 

AM: Sunscreen 

Midday: Sunscreen reapplication, lotion, stick or spray.

PM: Pigment corrector of choice (tranexamic acid, ascorbic acid, azelaic acid, hydroquinone)

Weekly: Lactic acid + Glycolic acid 

Note: The greatest traction of any melasma skincare routine is the correct application of sunscreen. This has a much greater impact on melasma than any marketing objective of any skin care ingredient. 

What are the best brands of lactic acid?

Here are our favorites.  

AHA Elucent: bang for your buck. The Elucent Anti-aging Serum contains 16% AHA, with 12% lactic & 4% glycolic. 

The Ordinary: produces a very cost effective formulation of 10% lactic acid + HA serum at just over 11 dollars. They also have a 5% lactic acid formulation for a dollar less. You get what you pay for. 

Cerave has a product called Skin Renewing Nightly Exfoliating Treatment that contains a blend of AHAs namely glycolic & lactic acids at 5% concentration. It is also fortified with hyaluronic acid & ceramides. We find this a better product compared to The Ordinary. 

How do I perform a DIY lactic acid peel at home?

The safety of performing a lactic acid peel at home is related to your IQ levels. Executed correctly can potentially lighten melasma pigmentation. Performed wrongly it can lead to worsening of melasma as well as a chemical burn. 

Here’s a step-by-step guide. 

1. Choose the correct Lactic Acid Product Select a product specifically labeled as a peel with a concentration between 5% and 30% for home use. Beginners should start with lower concentrations. Match the peel to your skin type & skin sensitivity.
2. Perform a Patch Test. Apply a small amount of the product to an inconspicuous area (like behind your ear or inner forearm). Wait 24-48 hours to check for irritation, redness, or an allergic reaction. We don’t perform test patches, but if you want to roll the dice for DIY lactic acid peel, perform a test patch.
3. Prepare Your Skin. Cleanse: Wash your face with a gentle, non-abrasive cleanser to remove dirt, oil, and makeup. Pat your skin dry; do not apply moisturizer or any other product.
4. Apply the lactic acid peel. Use a cotton pad or brush to apply the lactic acid solution evenly to your face, avoiding sensitive areas like the eyes, lips, and nostrils.Start with a thin layer to prevent over-exfoliation. The concentration depends on your skin type & sensitivities.
5. Monitor the Peel. Leave the peel on for the recommended time (usually 1–5 minutes for beginners).If you feel excessive burning or irritation, rinse it off immediately. If you over cook it, your melasma will worsen.
6. Rinse off. Thoroughly rinse your face with cool water to neutralize the acid. Avoid scrubbing while rinsing.
7. Soothe Your Skin. Apply a hydrating, fragrance-free moisturizer or soothing gel (e.g., aloe vera) to replenish moisture.Use a broad-spectrum sunscreen (SPF 50 or higher) as your skin will be more sensitive to the sun.
8. Post-Peel Care. Avoid retinoids, AHAs, or other active ingredients for at least 24–48 hours. Do not use makeup or harsh cleansers immediately after the peel.

Tips for Safe Use. 

1. Use peels no more than once a week, and gradually increase frequency as tolerated.
2. Stay Sun-Safe: Wear sunscreen daily and limit sun exposure. This is obvious as your melasma is sun exacerbated in the first place.
3. Avoid it if you have open wounds, active infections, or are using prescription skin treatments.

*We don’t endorse DIY at home peels, however there is a subgroup of Reddit keyboard warriors who insist on being experts. The above method will at least give a safe starting point for those inclined to try it at home. 

What do the studies say about lactic acid for melasma?

Studies have shown that lactic acid, lactic acid can be effective in the treatment of melasma and pigmentation disorders due to its exfoliating and skin-lightening properties.

Effectiveness in Melasma Treatment: A study compared the use of lactic acid peels with glycolic acid peels in melasma patients. Both treatments showed significant improvement in reducing Melasma Area and Severity Index (MASI) scores. Patients treated with lactic acid experienced fewer side effects, such as burning and erythema, making it a suitable option for sensitive skin. Lactic acid peels were particularly effective in improving skin quality, reducing hyperpigmentation, and lightening melasma-affected areas.

Mechanism of Action: Lactic acid works by exfoliating the epidermis, promoting cell turnover, and reducing the appearance of pigmented lesions. It also stimulates collagen production, further improving skin texture and clarity. For more details, you can explore studies like those published in the International Journal of Research in Dermatology. 

Can lactic acid lighten skin?

Lactic acid is a good way to lighten & brighten skin, especially in combination with other exfoliators. We prefer compounded formulations ranging from 5% to 12% in a moisturing base. 

For skin whitening, we combine lactic acid with polypodium & glutathione as well as pico lasers. 

Are lactic acid peels the best for melasma?

Though AHA peels are useful for melasma (especially in combination with other skin care actives), we prefer novel formulations of peeling agents or better still, pico lasers. 

Better peel formulations for melasma include-

• Cosmelan 
• Vi Precision Plus

Can I use lactic acid long term?

Unlike hydroquinone, AHAs such as lactic & glycolic acid can be used long term. 

Used in pulse therapy glycolic & lactic acid provides strong exfoliation at intervals (our preferred method). In contrast, used nightly it provides mild exfoliation. Nightly use is easier to modulate compared to pulsed therapy. Be guided by your clinician as to what application method is best for your melasma pigmentation.  

Can lactic acid be used in pregnancy?

Yes, glycolic, lactic, mandelic & azelaic acids can be safely used in pregnancy. Niacinamide is also safe in pregnancy.

Ingredients not recommended in pregnancy include: Vitamin A / retinol/retinoids, hydroquinone.