Lactic acid may sound like something you’d only encounter in a lab or a workout session, but it’s actually one of skincare’s most powerful secret weapons. Found naturally in fermented foods like yogurt and produced by the body during exercise, this alpha hydroxy acid (AHA) has carved out a prominent place in the beauty world for its gentle yet effective exfoliating properties.
Unlike harsher acids that can strip the skin, lactic acid works by dissolving the bonds between dead skin cells on the surface, revealing a fresher, more radiant layer beneath. But its benefits don’t stop there—it also hydrates, brightens, smooths, and helps tackle common concerns like fine lines, pigmentation, and acne.
Of course, with any active skincare ingredient, there are precautions to keep in mind. Overuse or incorrect application can lead to irritation, dryness, or even damage to your skin barrier. That’s why understanding how lactic acid works, when to use it, and whether it’s right for your skin type is essential. In this guide, we’ll walk you through 15 science-backed benefits, common side effects, usage tips, and key precautions to help you get the most out of lactic acid—safely and effectively.
What is Lactic Acid?
Lactic acid is an organic compound that plays a crucial role in various biological and industrial processes. Naturally present in the human body, it is produced during anaerobic respiration when oxygen levels are low. This typically happens during intense physical activity, causing a temporary buildup of lactic acid in muscles, which leads to the familiar burning sensation. Aside from its physiological role, lactic acid is also a widely-used alpha hydroxy acid (AHA) in the skincare and cosmetic industry due to its gentle exfoliating and moisturizing properties.
Historically, lactic acid was first isolated from sour milk by the Swedish chemist Carl Wilhelm Scheele in 1780. It gets its name from the Latin word “lac,” which means milk. Today, lactic acid is synthetically produced through fermentation of carbohydrates like glucose or lactose using specific bacterial strains such as Lactobacillus. It is used not only in skincare but also in food preservation, pharmaceutical products, and biodegradable plastics.
In skincare, lactic acid is known for its ability to exfoliate the skin, improve hydration, and boost collagen production. It gently dissolves the bonds between dead skin cells, allowing them to shed more efficiently and paving the way for healthier, glowing skin underneath.
Properties of Lactic Acid
| Property | Description |
|---|---|
| Chemical Formula | C3H6O3 |
| Molecular Weight | 90.08 g/mol |
| Appearance | Colorless to yellowish, clear liquid |
| Odor | Slightly acidic, sour smell |
| pH | Generally between 2.5 and 3.8 (depending on concentration) |
| Solubility | Soluble in water and alcohol |
| Melting Point | 16.8 °C |
| Boiling Point | 122 °C at 15 mm Hg |
| Density | 1.209 g/cm³ |
| Functional Group | Carboxylic acid and hydroxyl group |
| Natural Sources | Sour milk, yogurt, fermented vegetables, muscles post-exercise |
| Industrial Production | Fermentation of sugars using Lactobacillus species |
| Classification | Alpha Hydroxy Acid (AHA) |
How Does Lactic Acid Work?
Lactic acid works through a combination of chemical exfoliation and moisture retention. As an alpha hydroxy acid, it breaks down the desmosomes—protein bonds that hold dead skin cells together on the surface of the skin. This encourages the removal of these cells, promoting quicker cell turnover and revealing fresher, brighter skin underneath.
Additionally, lactic acid acts as a humectant, attracting water molecules to the skin and helping it retain moisture. This is especially beneficial for people with dry or dehydrated skin. Unlike harsher exfoliants, lactic acid’s larger molecular size allows it to work on the surface layer of the skin without deeply penetrating and potentially irritating sensitive skin.
Lactic acid also boosts the skin’s natural barrier by stimulating the production of ceramides—lipids that help the skin retain moisture and defend against environmental stressors. Over time, consistent use can improve the skin’s texture, tone, and elasticity.
15 Science-Backed Benefits of Lactic Acid
1) Exfoliates Dead Skin Cells: Gently removes dead cells, leaving skin smoother.
2) Improves Skin Texture: Helps with rough, bumpy skin and smooths uneven patches.
3) Brightens Dull Skin: Reveals fresh layers of skin, improving radiance.
4) Fades Hyperpigmentation: Treats dark spots, melasma, and sun damage over time.
5) Stimulates Collagen Production: Supports skin structure and reduces sagging.
6) Improves Skin Hydration: Its humectant nature helps draw moisture to the skin.
7) Minimizes Fine Lines and Wrinkles: Encourages smoother, plumper skin with continued use.
8) Reduces Acne: Clears clogged pores and minimizes whiteheads and blackheads.
9) Evens Skin Tone: Reduces the appearance of blotchiness and uneven pigmentation.
10) Improves Cell Turnover: Promotes healthier, newer skin coming to the surface.
11) Softens Rough Patches: Useful in conditions like keratosis pilaris or calluses.
12) Balances Skin pH: Maintains the slightly acidic environment necessary for skin health.
13) Enhances Product Absorption: Prepares the skin to absorb serums and creams more effectively.
14) Reduces Appearance of Scars: Lightens post-acne pigmentation and textural scars.
15) Gentle for Sensitive Skin: Less irritating than other AHAs like glycolic acid, making it suitable for more skin types.
10 Side Effects of Lactic Acid
1) Skin Irritation: May cause stinging or redness, especially for first-time users.
2) Increased Sun Sensitivity: Makes the skin more vulnerable to sunburn and UV damage.
3) Dryness or Peeling: Can over-exfoliate, especially in dry climates or with excessive use.
4) Allergic Reactions: In rare cases, causes rashes or hives.
5) Photosensitivity: Skin becomes more reactive to sunlight; sunscreen is mandatory.
6) Breakouts: Initial purging phase may trigger temporary breakouts.
7) Inflammation: Possible if overused or combined with other strong actives.
8) Eye Irritation: Harmful if it enters the eyes—always avoid the eye area.
9) Interactions with Other Products: Should not be used with retinoids or strong acids.
10) Barrier Damage: Weakens the skin barrier if used too frequently or without moisturizing.
How to Use Lactic Acid
- Start with a Low Concentration: Choose products with 5% or lower to test sensitivity.
- Patch Test First: Apply a small amount on the inner forearm and wait 24 hours.
- Apply at Night: Skin is more receptive at night and less exposed to UV rays.
- Avoid Mixing with Other Actives: Especially retinoids, benzoyl peroxide, and other AHAs/BHAs.
- Follow with Moisturizer: Hydration helps minimize potential dryness or irritation.
- Use Sunscreen Daily: Apply broad-spectrum SPF 30 or higher every morning.
- Apply on Clean, Dry Skin: Helps lactic acid work more efficiently.
- Use 2-3 Times a Week: Gradually increase frequency if your skin tolerates it well.
- Choose Suitable Formulations: Opt for serums for stronger effects or creams for milder application.
- Consult a Dermatologist: Especially important for people with skin disorders or under medication.
Precautions and Warnings
- Avoid Eye Area: Lactic acid can be irritating if applied near the eyes.
- Pregnancy and Breastfeeding: Consult a healthcare provider before use.
- Do Not Overuse: Overuse can lead to over-exfoliation and weakened skin barrier.
- Discontinue if Irritation Occurs: Rinse with water and stop using the product.
- Not for Broken Skin: Avoid using on areas with cuts, abrasions, or severe irritation.
- Photosensitivity Risk: Daily sun protection is essential.
- Store Properly: Keep in a cool, dry place and tightly sealed.
- Avoid Harsh Weather Conditions: Wind and cold can increase risk of irritation.
- Use Lower Concentrations First: Especially if you have sensitive or reactive skin.
- Check Ingredient Lists: Avoid using with alcohol-heavy or highly fragrant products.
Who Should Use Lactic Acid
- People with dry, dehydrated, or flaky skin needing gentle exfoliation.
- Individuals with dull complexion seeking a brighter appearance.
- Those with hyperpigmentation or sun damage looking for a gradual fade.
- People experiencing rough skin texture or keratosis pilaris.
- Individuals with fine lines, wrinkles, or other signs of aging.
- People with sensitive skin who react to stronger AHAs like glycolic acid.
- Anyone needing to prep skin for better absorption of serums and moisturizers.
- Individuals with non-inflammatory acne or clogged pores.
Who Should Not Use Lactic Acid
- People with highly sensitive or reactive skin.
- Those with rosacea, eczema, or chronic skin inflammation.
- Individuals on prescription acne treatments like isotretinoin or retinoids.
- People with active skin infections, cuts, or abrasions.
- Pregnant or breastfeeding women without medical clearance.
- Those who are outdoors frequently and not consistent with sun protection.
- Individuals with extremely dry or compromised skin barriers.
- Anyone with a history of allergies to AHAs or lactic acid-containing products.
FAQ’s
What is lactic acid used for in the face?
Lactic acid is used to exfoliate dead skin cells, brighten dull skin, fade dark spots, improve hydration, and promote smoother skin texture. It’s especially helpful for dry or sensitive skin types.
Is lactic acid safe for sensitive skin?
Yes, lactic acid is considered one of the gentler AHAs, making it suitable for sensitive skin when used in low concentrations. However, a patch test is always recommended before full application.
How often should I use lactic acid?
Beginners should start with 2–3 times per week. Once your skin adjusts, you may increase frequency as needed. Daily use is not necessary for most people.
Can I use lactic acid and retinol together?
No, it’s generally not recommended to use lactic acid and retinol together, especially at the same time, as this can cause irritation. Alternate them on different nights or consult a dermatologist.
Does lactic acid help with acne?
Yes, lactic acid can help unclog pores, reduce blackheads and whiteheads, and promote cell turnover, which may improve mild to moderate acne.
Will lactic acid make my skin peel?
Mild peeling can occur, especially when first using the product or if it’s applied too frequently. This is a normal exfoliation response but should be monitored to avoid overuse.
Can I use lactic acid daily?
It’s best to begin slowly and observe your skin’s response. Some advanced users tolerate daily use, but overuse can damage the skin barrier and cause irritation.
What percentage of lactic acid is best for beginners?
Products with 5% or lower concentration are ideal for beginners. These provide effective exfoliation without overwhelming the skin.
Do I need to wear sunscreen after using lactic acid?
Absolutely, Lactic acid increases sun sensitivity, so daily use of a broad-spectrum SPF 30 or higher is essential to prevent sunburn and damage.
Can pregnant or breastfeeding women use lactic acid?
Low concentrations of lactic acid are generally considered safe, but it’s important to consult a healthcare provider before use during pregnancy or breastfeeding.
What is lactic acid mainly used for?
Lactic acid is primarily used in skincare for gentle exfoliation, improving skin texture, fading dark spots, and enhancing hydration. It removes dead skin cells from the surface, promoting a brighter and smoother complexion.
What is the best time to use lactic acid?
The best time to use lactic acid is at night, when your skin can repair itself without exposure to sunlight. Using it before bed also reduces the risk of sun sensitivity during the day.
Does lactic acid brighten skin?
Yes, lactic acid can brighten the skin by removing dull, dead skin cells and promoting new cell turnover. Over time, this leads to a more radiant and even-toned appearance.
Is lactic acid found in curd?
Yes, lactic acid is naturally produced during the fermentation of milk, so it is found in curd, yogurt, and other fermented dairy products. However, these natural sources are much milder than the concentrated forms used in skincare products.
Can lactic acid remove tan?
Lactic acid can help fade tan by exfoliating the top layer of pigmented skin. While it won’t provide instant results, consistent use may lighten sun-induced discoloration over time.
Does lactic acid thicken skin?
Lactic acid doesn’t directly thicken the skin, but by stimulating collagen production, it can improve skin firmness and elasticity, giving the skin a plumper appearance.
Does lactic acid make you glow?
Yes, by promoting smoother texture and increasing cell turnover, lactic acid can give your skin a healthy, natural glow. Many users notice radiance within a few weeks of consistent use.
Which is better, lactic acid or salicylic acid?
It depends on your skin type and concerns.
- Lactic acid is best for dry, sensitive, or aging skin needing hydration and surface exfoliation.
- Salicylic acid is ideal for oily, acne-prone skin as it penetrates deep into pores to clear excess oil and bacteria.
Which brand of lactic acid is best?
Some highly-rated lactic acid products include:
- The Ordinary Lactic Acid 5% or 10% + HA
- Sunday Riley Good Genes Lactic Acid Treatment
- Paula’s Choice Skin Revealing Body Lotion with 10% AHA
Always choose a brand that suits your skin type and budget, and patch test before full use.
Which is better, niacinamide or lactic acid?
Both have distinct benefits:
- Niacinamide helps with oil control, redness, enlarged pores, and strengthens the skin barrier.
- Lactic acid excels at exfoliating, brightening, and hydrating the skin.
You can even use both in your routine (at different times) for complementary effects.
What is the best age to use lactic acid?
Lactic acid can be safely used starting in your early 20s, especially if you’re dealing with dull skin, rough texture, or early signs of aging. Teens with acne may also benefit under guidance.
Is lactic acid better than retinol?
They serve different purposes:
- Lactic acid exfoliates and hydrates the skin.
- Retinol promotes deeper skin renewal and collagen synthesis.
For anti-aging, retinol is stronger, but lactic acid is gentler and more hydrating, making it ideal for sensitive skin or beginners.
Which is better, vitamin C or lactic acid?
- Vitamin C is a powerful antioxidant that brightens skin and fights free radicals.
- Lactic acid exfoliates and improves skin texture.
They work well together but should be used carefully (often at different times of day) to avoid irritation.
Conclusion
Lactic acid is a versatile and powerful ingredient that offers a wide array of benefits, particularly for those looking to improve skin texture, tone, and hydration. Its gentle nature makes it suitable for a broader range of users, including those with sensitive skin. However, its effectiveness requires thoughtful application and an awareness of potential side effects. By starting slow, pairing it with hydrating ingredients, and never skipping sunscreen, users can safely enjoy the long-term skin benefits lactic acid has to offer. Always consult a skincare professional if you’re uncertain about incorporating it into your routine.
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