Lactic acid doesn’t get as much spotlight as some of its AHA cousins like glycolic acid, but maybe that’s part of its charm. It’s quietly powerful—gentler on the skin, yet still remarkably effective. If you’ve ever wondered what makes lactic acid a staple in so many skin treatments, or if you’re curious whether it’s the right fit for your routine, this deep dive will cover everything you need to know.

What Is Lactic Acid?

Lactic acid is a type of alpha hydroxy acid (AHA), a class of water-soluble acids commonly derived from fruits and milk (though most modern formulas use synthetically produced versions for consistency and safety). Historically, it’s said Cleopatra bathed in sour milk to reap its skin-smoothing benefits—turns out, she might’ve been onto something.

Chemically, lactic acid is a larger molecule than glycolic acid, which means it doesn’t penetrate the skin as deeply. This can be a good thing. It makes lactic acid less likely to cause irritation while still delivering visible exfoliation and hydration.

What Are the Benefits of Lactic Acid?

1. Gentle Exfoliation

At its core, lactic acid is an exfoliant. It works by breaking down the bonds between dead skin cells on the surface of the skin, allowing them to slough off more easily. This encourages a smoother texture and more even tone over time.

Unlike physical scrubs, which can create micro-tears in the skin, chemical exfoliants like lactic acid work more evenly and with less mechanical trauma.

2. Improved Skin Texture and Radiance

With regular use, lactic acid can soften rough patches, diminish the appearance of fine lines, and give dull skin a healthy glow. It's particularly useful for people with dry or flaky skin who want gentle renewal without stripping moisture.

3. Hydration Booster

Here’s where lactic acid stands out among the AHAs—it’s also a humectant. That means it draws water into the skin, enhancing moisture levels. So not only does it exfoliate, but it also helps skin stay plump and hydrated. Think of it as doing double duty.

4. Supports Skin Cell Turnover

Lactic acid encourages a faster rate of cell turnover, helping your skin renew itself more efficiently. Over time, this can reduce the visibility of hyperpigmentation, acne scars, and sun damage.

5. Promotes a Healthier Skin Barrier

At appropriate concentrations, lactic acid has been shown to increase ceramide production in the skin—lipids that strengthen your skin barrier. A strong barrier helps retain moisture and keeps out irritants.

How to Use Lactic Acid in Your Routine

Using lactic acid isn’t complicated, but there are a few best practices to follow so you get the benefits without the backlash.

1. Start Low and Slow

If you’re new to acids, begin with a lower concentration—typically around 5%. You might find this in overnight treatments or toners. Use it 1–2 times per week to start. As your skin adjusts, you can build up to higher strengths (10% is a common ceiling for at-home use).

2. Use It at Night

Because lactic acid can make your skin more sensitive to sunlight, nighttime application is generally preferred. Plus, skin tends to regenerate while you sleep, making this a good time to introduce actives.

3. Always Wear Sunscreen

Daily SPF is a non-negotiable when using AHAs. Lactic acid can increase your skin’s sensitivity to UV radiation, so applying sunscreen every morning helps prevent damage and discoloration.

4. Don’t Mix Everything at Once

Avoid using lactic acid in the same routine as other potent actives like retinoids, vitamin C (ascorbic acid), or benzoyl peroxide unless you’re confident your skin can tolerate it. Overloading your skin can lead to redness, peeling, or inflammation.

5. Moisturize Generously

Pairing lactic acid with a good moisturizer helps soothe the skin and maintain hydration, especially after exfoliation. Ingredients like ceramides, niacinamide, or hyaluronic acid can complement lactic acid well.

What Are the Risks and Side Effects?

Lactic acid is generally well-tolerated—especially compared to stronger AHAs—but it's not risk-free.

Common Side Effects:

• Tingling or mild burning upon application, especially for beginners.
• Dryness or flakiness if overused or combined with too many other exfoliants.
• Increased sun sensitivity, which can lead to sunburn if not protected against.

Rare but Possible:

• Contact dermatitis in people with sensitive or compromised skin.
• Hyperpigmentation in darker skin tones if overused without sun protection.

If you experience ongoing irritation, it’s best to dial back the frequency or consult a dermatologist.

Are There Different Types of Lactic Acid?

In the context of skincare, there are two key distinctions worth understanding:

1. L-Isomer vs D-Isomer

Lactic acid has two isomers: L-lactic acid and D-lactic acid. The L-isomer is the one most often used in skincare—it’s biologically active and more effective for exfoliation. Some formulations include racemic (mixed) blends, but the L-form is generally preferred for results.

2. Natural vs Synthetic Sources

As mentioned earlier, natural lactic acid can be derived from milk, fruit sugars, or fermented vegetables. Synthetic versions are chemically identical but offer more consistency and less risk of bacterial contamination. Most high-quality skincare uses lab-made lactic acid, and that's a good thing.

Pros and Cons of Lactic Acid

ProsConsGentle exfoliant suitable for sensitive skinCan cause irritation if overusedAlso hydrates the skin (humectant properties)Sun sensitivity increases with useImproves skin texture and glowNot suitable for open wounds or raw skinPromotes ceramide productionMay require weeks to see full resultsWidely available in many product typesSlight tingling may be unpleasant for some

What Kinds of Products Contain Lactic Acid?

Lactic acid shows up in a variety of skincare formats, depending on what you're trying to achieve. Here’s a breakdown of the most common:

1. Serums

These are often more concentrated and used for overnight treatments. The Ordinary’s Lactic Acid 5% + HA and Sunday Riley’s Good Genes are popular examples.

2. Toners and Exfoliating Pads

Toners like The Inkey List Lactic Acid or First Aid Beauty Facial Radiance Pads offer low-dose daily or every-other-day exfoliation.

3. Cleansers

These provide very gentle exfoliation without the long contact time. They’re ideal for ultra-sensitive skin or beginners.

4. Masks and Peels

Formulas with 10–30% lactic acid are typically used as rinse-off masks. These offer a more intensive exfoliation in a shorter time frame—usually once a week.

5. Body Lotions

Lactic acid is incredibly effective for conditions like keratosis pilaris (“chicken skin”) and rough patches on elbows or knees. Products like AmLactin or Paula’s Choice Weightless Body Treatment combine exfoliation with moisturization.

Is Lactic Acid Right for You?

• If you have sensitive or dry skin, lactic acid is one of the best exfoliating acids you can choose.
• If you’re dealing with hyperpigmentation or dullness, it helps even out tone over time.
• If your skin is acne-prone, it may help, though salicylic acid (a BHA) is typically preferred for deeper pore exfoliation.

Still not sure? Look for lactic acid in a multi-acid formula that also includes hydrating or calming ingredients. That way, you get the benefits in a more buffered delivery.

Final Thoughts

Lactic acid is like that friend who’s calm and reliable—but don’t mistake its gentleness for weakness. It’s a powerful tool when used right: exfoliating, hydrating, and promoting long-term skin health with minimal risk of irritation. Whether you’re chasing radiance, smoother skin, or a more even complexion, lactic acid can be a worthy (and underrated) addition to your routine.

Just go slow, wear sunscreen, and listen to your skin. Because sometimes, less really is more.

‍