Lactic Acid
Also known as: 2-Hydroxypropanoic acid
Key Takeaways
- Lactic acid is the gentlest AHA, making it the best entry point for chemical exfoliation for sensitive and dry skin types
- Its larger molecule size reduces irritation while its humectant properties add hydration — a unique dual benefit
- Effective at 5-12% for improving texture, dullness, and mild hyperpigmentation
- Always use SPF when incorporating lactic acid into your routine
The gentlest AHA exfoliant, with a larger molecular size than glycolic acid that makes it ideal for sensitive and dry skin types. Simultaneously exfoliates and hydrates, making it one of the most beginner-friendly chemical exfoliants available.
Skin Type Compatibility
Skin Tone Notes
Effective for hyperpigmentation across all Fitzpatrick types. Deeper skin tones should patch test and start low to avoid post-inflammatory hyperpigmentation from over-exfoliation.
What It Does
Lactic acid loosens the bonds between dead skin cells on the surface, allowing them to shed more easily. Its larger molecule size means it penetrates less deeply than glycolic acid, resulting in effective exfoliation with less irritation. As an alpha-hydroxy acid, it also has humectant properties that draw moisture into the skin, making it uniquely hydrating among chemical exfoliants.
Concerns Addressed
How To Use
Apply in the PM after cleansing and before moisturizer. Begin with 2-3 times per week, increasing frequency as your skin adjusts. Always follow with SPF in the morning. Avoid using on the same evening as retinol or other strong actives.
Pairs Well With
Hyaluronic Acid
A naturally occurring polysaccharide that can hold up to 1000 times its weight in water. Hyaluronic acid is one of the most effective and universally tolerated hydrating ingredients in skincare, working for every skin type and pairing seamlessly with virtually all actives.
Niacinamide
A form of vitamin B3 that strengthens the skin barrier, reduces inflammation, and regulates sebum production. One of the most versatile and well-studied active ingredients in modern skincare.
Avoid Combining With
Both increase cell turnover and skin sensitivity. Combining them raises the risk of over-exfoliation, barrier disruption, and irritation.
Side Effects
Mild tingling or stinging on first application is normal, especially at higher concentrations. Increases photosensitivity — daily SPF use is essential. Overuse can lead to redness, dryness, or a compromised skin barrier. Start with 2-3 times per week and build up gradually.
Key Studies
Lactic acid significantly improved skin texture, tone, and smoothness with a favorable tolerability profile, particularly for sensitive skin types.
Topical lactic acid increased ceramide production and improved stratum corneum hydration, confirming its dual exfoliant-humectant role.
What Is Lactic Acid?
Lactic acid is an alpha-hydroxy acid (AHA) naturally found in milk, fermented foods, and even produced by the body during exercise. In skincare, it is synthesized for consistency and purity. It holds the distinction of being the gentlest AHA available, largely due to its larger molecular size compared to glycolic acid, which limits how deeply it penetrates the skin.
How Does Lactic Acid Work?
Lactic acid works by disrupting the bonds between corneocytes — the dead skin cells that make up the outermost layer of the stratum corneum. By breaking these bonds, it encourages the natural shedding process, revealing fresher, more even-toned skin underneath. Beyond exfoliation, lactic acid functions as a humectant, drawing water molecules into the skin, which explains why it is uniquely hydrating among chemical exfoliants.
Who Should Use Lactic Acid?
Lactic acid is an ideal starting point for anyone new to chemical exfoliation, and it remains a staple for experienced users with dry or sensitive skin. It is particularly well-suited for those who have found glycolic acid too irritating, anyone dealing with dull or rough texture, and people looking to address mild hyperpigmentation without sacrificing hydration.
Frequently Asked Questions
How is lactic acid different from glycolic acid?
Lactic acid has a larger molecular size than glycolic acid, which means it penetrates the skin less deeply. This makes it gentler and better tolerated, especially for sensitive or dry skin, while still delivering effective exfoliation and brightening.
Can I use lactic acid every day?
Most people should start at 2-3 times per week and increase gradually. At lower concentrations (5-8%), daily use may be tolerable once your skin has adjusted. Higher concentrations (10-12%) are best used a few times per week to avoid over-exfoliation.
Does lactic acid help with hyperpigmentation?
Yes. Lactic acid accelerates the shedding of pigmented surface cells and has some evidence for inhibiting melanin production at higher concentrations. For significant hyperpigmentation, pairing it with niacinamide enhances results without increasing irritation.