The Complete Guide To Using Lactic Acid

Lactic acid is an alpha hydroxy acid (AHA) that can offer multiple skin benefits and address various skin concerns, from hyperpigmentation, fine lines and wrinkles, and rough, uneven skin texture.

However, like every other ingredient, lactic acid needs to be used correctly and with caution to avoid any potential side effects.

Therefore, if you want to introduce this multi-tasking active into your skincare routine but don’t know if it’s right for you or how to start using it without experiencing adverse effects, continue reading.

In this complete guide to using lactic acid, I will cover everything you need to know about this AHA, its benefits, potential side effects, and how to incorporate it into your skincare routine to address your skin concerns and improve your skin’s health and appearance. 

What is Lactic Acid?

Lactic acid is an exfoliating acid derived from sour milk or sugar-rich foods and a water-soluble component with a large molecular weight that plays a crucial role in various biochemical processes.

In skincare, lactic acid is predominantly used to exfoliate the skin by breaking down the bonds between the outer layer of skin cells, allowing for their easy removal.

Due to its large molecules, lactic acid won’t penetrate deeper into the skin and will instead work on the surface, which leads to a lighter degree of exfoliation, which is more suitable for sensitive skin types.

How Does Lactic Acid Work?

Lactic acid, an alpha hydroxy acid (AHA), works on the skin’s surface, dissolving the protein bonds that hold dead skin cells to the surface.

It does this by lowering the skin’s pH, resulting in an acidic environment.

In this environment, the molecular structure of the intercellular lipid matrix, which holds the dead skin cells onto the skin’s surface, starts to break down.

This process allows dead skin cells to be sloughed off more effectively, revealing a fresher, more radiant complexion underneath.

Lactic acid is naturally present in the gut and skin and contributes to the cell cycle in human keratinocytes (the skin cells.)

Additionally, lactic acid is a part of the skin’s natural moisturizing complex; therefore, it helps hydrate the skin and regulate trans-epidermal moisture loss.

The Benefits of Lactic Acid

Here are several benefits of lactic acid for the skin:

Exfoliation: Lactic acid dissolves the glue that binds dead skin cells to the surface, promoting faster skin cell turnover and a radiant complexion.

Moisturization: Lactic acid improves skin hydration by attracting and retaining moisture in the skin due to its humectant properties.

Reduction of Age Spots: Regular use of lactic acid can lighten age spots and hyperpigmentation, as it accelerates the shedding of pigmented cells.

Smoothing of Fine Lines and Wrinkles: By promoting new cell growth, lactic acid helps to smooth out fine lines and wrinkles for a more youthful appearance.

Improvement of Skin Texture: Lactic acid refines the skin’s surface by getting rid of rough patches, leading to a softer and smoother skin texture.

Reduction of Acne: Lactic acid is beneficial for acne-prone skin as it dissolves dead skin cells on the skin’s surface, which helps new skin cells travel to the surface instead of remaining stuck inside the pores and creating clogs.

The Side Effects of Lactic Acid

While generally well-tolerated by all skin types, including sensitive skin, incorrect use of lactic acid can lead to side effects, such as:

• Skin irritation: Overusing lactic acid can cause skin irritation as the ingredient removes the outer layer of skin cells, exposing the sensitive new skin underneath.
• Dryness: Overusing lactic acid can lead to dryness as it can strip the skin of its natural oils during exfoliation.
• Photosensitivity: Lactic acid can make your skin more susceptible to sunburn, as the newer skin cells exposed after exfoliation are more sensitive to the sun’s rays.
• Purging: Some users may experience a purging phase where breakouts get worse before they get better due to the accelerated turnover of skin cells.
• Stinging Sensation: Some people may experience a mild stinging or burning sensation immediately after applying lactic acid due to its acidic nature.

Lactic Acid Step-by-Step Guide for Beginners

Lactic acid is a mild exfoliating acid that can address various skin concerns, including pigmentary issues, inflammatory conditions such as acne, and aging concerns such as lines and wrinkles.

However, it can also cause several uncomfortable side effects if used incorrectly.

Therefore, as a beginner, following the correct steps when incorporating lactic acid into your skincare routine is essential to ensure you get the skin benefits this ingredient offers and avoid potential adverse effects.

Here’s a detailed step-by-step guide for beginner’s use of lactic acid:

Step 1: Understand Your Skin

Lactic acid is a fantastic ingredient that can help address several skin concerns; however, that doesn’t mean it will suit your skin.

Therefore, if you decide to test a new active ingredient you’ve never tried before, you need to start by understanding your skin, how it reacts when something doesn’t agree with it, and its current state.

For example, if your skin is normal to dry, you might see a positive response to lactic acid since it has hydrating properties.

However, if your skin is sensitive or you’re currently experiencing irritation, it may not be the best time to introduce an agent that will temporarily strip your barrier, as this may lead to a more severe reaction.

On the other hand, if your skin is oily and you are currently dealing with acne, lactic acid may again be helpful as it technically ticks two boxes – exfoliation and sebum control, which can help maintain the inflammatory condition and keep excess oiliness under control.

However, because your skin is inflamed due to acne (an inflammatory condition), it may not take too well to being stripped by exfoliation and may rebel by becoming more inflamed, which will lead to exacerbated acne.

Therefore, it is essential to understand your skin and its current state while incorporating a new active ingredient so that you can promptly spot any adverse reactions and prevent a potentially bigger issue.

Step 2: Choose The Right Concentration

Lactic acid is available in various concentrations, ranging from less than 5% to up to 10% in over-the-counter products.

As a beginner, it’s best to start with a lower concentration and gradually work your way up.

A concentration of 5-10% is considered mild and suitable for beginners and an excellent place to start when trying lactic acid for the first time.

Even if your skin is resilient and used to other exfoliating acids, starting low and working your way up is still a good idea.

This will give your skin time to adjust to the new ingredient and avoid potential irritation or dryness.

Step 3: Patch Test

Patch testing is essential when incorporating any new active ingredient into your skincare routine, especially if you have sensitive skin.

To patch test lactic acid, apply a small amount of the product on a discreet area, such as behind your ear, where it will sit for at least a few hours without being washed off.

If you experience moderate to severe redness, itching, or burning sensations when it’s on your skin, rinse it off immediately, and do not use the product on your face.

Step 4: Correct Lactic Acid Application And Use

As an exfoliating acid, lactic acid should always be applied in your nighttime skincare routine.

Exfoliating in the morning can make your skin more sensitive to the sun, leading to adverse effects like photosensitivity.

Here is an easy step-by-step guide on how to correctly apply lactic acid as a beginner:

1. Cleanse with a gentle cleanser and allow your skin to dry naturally.
2. Apply a thin layer of toner or essence to balance your skin’s pH and prepare it for the active ingredient.
3. Apply a small amount of lactic acid over the face and neck, avoiding the eye and lip area. If you are using a lactic acid serum, apply a pea-sized amount. If you are using a lactic acid toner, apply a thin layer to avoid over-exfoliation.
4. Frequency: Initially, use lactic acid once a week in the evening. After 1-2 weeks of use with no adverse reactions, you can gradually increase the frequency to twice and a maximum of three times a week. Avoid using lactic acid more frequently than three times a week to give your skin cells time to rejuvenate without stripping them away too quickly.

Step 5: Post-Application Care

• Moisturizer: Once the lactic acid has been absorbed into the skin, follow up with a nourishing moisturizer to help lock in the active ingredient while strengthening the skin barrier to prevent trans-epidermal moisture loss.
• Sunscreen: Make sure to apply sunscreen the following morning, as exfoliating agents like lactic acid can increase your skin’s sensitivity to the sun. Choose a broad-spectrum sunscreen with an SPF of 30 or higher for optimal protection.

Step 6: Monitor Your Skin’s Reaction

• Observation: Look for signs of irritation like redness, burning, dryness, peeling, and flaking. If these occur, reduce the frequency of lactic acid use.
• Adjustment: Depending on your skin’s tolerance, you can gradually increase the frequency of use and the concentration of lactic acid over time.

Step 7: Integrate into Routine

• Routine Integration: Once your skin has adapted, incorporate lactic acid into your regular skincare routine, balancing it with other skincare products.
• Avoid Overuse: Be careful not to over-exfoliate. Pay attention to your skin’s needs and responses.
• Active Integration: Since lactic acid is an exfoliant, it’s best to avoid combining it with other active ingredients with exfoliating properties, as this can lead to over-exfoliation and irritation.

Lactic Acid Dos and Don’ts

Here are some final dos and don’ts to keep in mind when using lactic acid:

• DO a patch test first: Before applying any lactic acid product to your face, it’s important to do a patch test to see how your skin reacts.
• DO Start with a lower concentration: If you’re new to lactic acid, start with a lower concentration product to allow your skin to adjust.
• DO Apply at night: Lactic acid can make your skin more sensitive to the sun, so it’s best used in your nighttime skincare routine.
• DO Use sunscreen during the day: Protect your skin from sun damage by applying a broad-spectrum SPF during the day.
• DO Have a Complete Skincare Routine: Lactic acid will give you the best results when incorporated into a complete skincare routine with products it works well with.

On the other hand, here are some don’ts to keep in mind when starting to use lactic acid:

• DON’T Use on Wet Skin: Applying lactic acid on wet skin can increase permeability and lead to irritation. Always apply it on dry skin.
• DON’T Mix With Other Actives: Avoid combining lactic acid with retinoids and other exfoliating ingredients to prevent barrier damage.
• DON’T Overuse: Overusing lactic acid can compromise the skin barrier and lead to dryness, irritation, and discomfort.
• DON’T Use on Damaged Skin: Avoid applying lactic acid to broken, damaged, or severely irritated skin, as this will increase discomfort and exacerbate inflammatory skin conditions.
• DON’T Ignore Adverse Reactions: If your skin experiences severe burning, redness, or peeling after using lactic acid, discontinue use and give your skin a break from active ingredients.

Can You Combine Lactic Acid With Other Actives?

You can combine lactic acid with the following active ingredients:

• Niacinamide: Combining niacinamide and lactic acid can fade hyperpigmentation, even out uneven skin tone, and refine texture.
• Hyaluronic acid: Combining hyaluronic acid and lactic acid can help increase hydration, soften the skin, and improve the appearance of fine lines and wrinkles.
• Peptides: Combining peptides and lactic acid can help refine skin texture and improve the appearance of fine lines and wrinkles.

On the other hand, avoid combining lactic acid with the following active ingredients:

• Exfoliating acids: Combining multiple exfoliating acids like salicylic acid, glycolic acid, or mandelic acid with lactic acid can lead to over-exfoliation and irritation.
• Benzoyl peroxide: Combining benzoyl peroxide with lactic acid can increase skin sensitivity and irritate the skin.
• Retinoids: Combining retinoids and lactic acid can lead to barrier damage, irritation, and dryness.

The Best Lactic Acid Products for Beginners

Here are some excellent lactic acid products with different price points you should take a look at:

The Ordinary – Lactic Acid 5%

Best for sensitive skin.

The Ordinary – Lactic Acid 5% is a fantastic, budget-friendly lactic acid serum with a beginner-friendly strength and a lightweight consistency.

Suitable for sensitive and reactive skin, the serum is further boosted with 2% hyaluronic acid to hydrate the skin and plump out irregularities.

Paula’s Choice – Smoothing Treatment 10% AHA

Best for oily, resilient skin.

The Paula’s Choice Smoothing Treatment 10% AHA Serum is formulated with a blend of exfoliating acids that help refine uneven skin texture, fade hyperpigmentation, even out uneven skin tone, and improve the overall skin appearance.

Lactic, glycolic, and malic acids work together to gently exfoliate the skin, while licorice root extract helps brighten and even out skin tone while green tea extract and chamomile help soothe and hydrate the skin. 

Biossance – Squalane Lactic Acid Resurfacing Night Serum

Best for dry skin.

The Squalane Lactic Acid Resurfacing Night Serum by Biossance is a gentle formula that combines 10% vegan lactic acid with squalane to exfoliate, hydrate, and improve skin texture.

It also contains rosehip oil and an array of nourishing components to soothe irritation and protect the skin from damage.

Sunday Riley – Good Genes All-in-One Lactic Acid Treatment 

Best for normal to dry skin.

The Good Genes All-in-One Lactic Acid Treatment by Sunday Riley is a cult favorite among skincare enthusiasts.

It contains 5% lactic acid, along with licorice and lemongrass to brighten the skin, improve texture, and reduce discoloration, as well as prickly pear extract and aloe vera to soothe redness and reduce the appearance of red acne marks.

It also helps refine the skin texture, which will minimize the appearance of pores and fine lines while providing hydration and nourishment for a radiant, glowing complexion. 

Vivant Skin Care – Derm-A-Renew

Best for all skin types.

The Derm-A-Renew by Vivant Skincare is a powerful yet gentle exfoliant containing lactic acid, along with Retinyl Propionate, an extremely gentle form of retinoid that exfoliates and promotes collagen production without causing irritation.

The lightweight serum also contains oligopeptides, antioxidants, and brightening components such as niacinamide, as well as hydrating ingredients such as urea to improve skin health, brighten the complexion, and reduce signs of aging.

Frequently Asked Questions

What Not to Use With Lactic Acid?

It’s best to avoid using lactic acid with other exfoliating acids, benzoyl peroxide, and retinoids.

These combinations can cause irritation and damage the skin barrier.

However, lactic acid can be safely combined with niacinamide, hyaluronic acid, and peptides.

When to Use Lactic Acid in Skincare Routine?

Lactic acid can be used at night after cleansing and toning the skin and before applying a moisturizer.

It’s important to use sunscreen during the day when using lactic acid as it can make your skin more sensitive to the sun.

What to Use After Lactic Acid?

After using lactic acid, it’s important to follow up with a moisturizer to hydrate and nourish the skin. 

What Percentage Of Lactic Acid is Most Effective?

The most effective percentage of lactic acid in an at-home treatment is between 5% for more sensitive skin types and 10% for more resilient skin types.

Additionally, lactic acid works best at a lower pH of around 3.5-4.0.

How To Start Using Lactic Acid?

It’s best to start introducing lactic acid into your skincare routine slowly by using it 1-2 a week in the beginning and following it up with a nourishing moisturizer and sunscreen in the morning.

Can You Use Lactic Acid If You Have Milk Allergy?

The lactic acid that goes into your skincare products won’t trigger your milk allergy because it’s synthetically produced and doesn’t contain dairy, which is what most people are allergic to.

But, if you are truly allergic to milk and get the most severe reactions, such as hives, shortness of breath, etc., you should talk to your health provider before using lactic acid products.

On the other hand, it is always helpful to test a product somewhere in a small area, like the inside on your wrist or behind your ear.

Especially with products such as The Ordinary Lactic Acid that cost around $10, even if you are sensitive to it or an allergic reaction happens, you can always give it to someone who might benefit from it.

Is It Okay To Use Lactic Acid Every Day?

Using lactic acid daily isn’t advised, as over-exfoliation can lead to a compromised skin barrier and exacerbate skin conditions such as acne, dermatitis, and rosacea.

Can Lactic Acid Cause Breakouts?

Yes, lactic acid can cause breakouts.

Lactic acid is an exfoliating acid that speeds up cellular turnover and pushes the gunk inside the pore to the skin’s surface.

This means that what would become a pimple in a few weeks will appear on the surface sooner.

This is called a “purging period” and is very common when using actives, so if you start getting some mild breakouts while using lactic acid, this is not something you should be afraid of.

However, if the “purge” becomes a bigger concern, such as severe breakouts or inflamed cystic acne, this likely means that the product you’re using isn’t working for you, and you should discontinue it.

Can You Mix Lactic Acid With Other Ingredients?

Can You Mix Glycolic Acid With Lactic Acid?

Can You Mix Niacinamide With Lactic Acid?

Can Lactic Acid and Hyaluronic Acid Be Used Together?

Can Retinol be Used With Lactic Acid?