Lactic Acid In Skin Care: The Benefits You Didn’t Know

Megan Dominion

Lactic acid is an alpha hydroxy acid (AHA) that’s derived from milk. Thinking of all those yogurt facials often recommended all over the internet and social media? Well, lactic acid is why. Often found in chemical peels, serums, and moisturizers, lactic acid is a popular ingredient in many skin-care products (and homemade facials.)

“Lactic acid is a great choice for those with sensitive skin because it’s very gentle,” says Joshua Zeichner, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City.

Have you been recommended a product that contains lactic acid, or already use one? I certainly have in the past. Find out exactly what the benefits of using lactic acid products are, and any potential side effects on your skin.

What is lactic acid?

Lactic acid is an organic compound that’s often found in milk and other dairy products. Interestingly, the compound is also produced by your muscles during strenuous. When used in skin care however, lactic acid is an alpha hydroxy acid (AHA) that breaks down dead skin cells on the surface of your skin. This can help to improve the appearance of wrinkles, fine lines, and dark spots. [1] This is a great example of a gentle chemical exfoliation (as opposed to a physical one – here’s the difference between a physical and chemical exfoliator for skin.

Can you use lactic acid if you have a dairy allergy?

Yes you can! If lactic acid is found in milk and dairy products, this raises the question of whether it is suitable for those who have a dairy or lactose allergy/sensitivity. The lactic acid ingredient listed on your product is not in fact dairy, but rather an organic compound that’s found IN dairy. It does not contain lactose. So rest assured, you can safely try out this product if you are lactose intolerant.

The benefits of lactic acid for skin

Lactic acid helps dissolve dead skin cells though exfoliation, leaving your skin feeling smooth and rejuvenated. It also speeds cell turnover and stimulates cell regeneration, the processes by which skin sheds old cells and regenerates new ones. It’s a great ingredient for exfoliating sensitive skin.

Products with latic acid in 12% concentrations has been noted to firm and thicken the skin. This results in fewer fine lines and deep wrinkles and an overall smoother appearance. Such high concentrations of lactic acid demonstrate the ability of the acid to penetrate deep into the skin. A concentration of about 5% has no effect on the middle layer of the skin. However, they have similar effects on a more superficial level. So take a look at what concentration of lactic acid is in your current or future skincare products and choose according to your skincare goals and skin sensitivity.

Lactic acid improves the appearance of your skin by making it brighter and smoother. AHA exfoliants can treat moderate to severe hyperpigmentation, which occurs when your skin has more melanin than it should, often the aftermath of an acne breakout. AHA exfoliants could also remove age spots, and wrinkles and diminish pore visibility. Since lactic acid is one of the mildest AHAs, it can be used in the correct amounts on sensitive skin. If your skin can handle something a bit stronger, alternatives include azelaic acid, glycolic acid (also an AHA) or retinols.

What to look for when buying products that contain lactic acid?

Lactic acid products can be found in various concentrations from 5% to more than 30%. However, a bigger percentage is not always preferable. Your skin may become irritated if you apply a high percentage of product straight away. Like retinols, you should rather  ease into a smaller percentage first, and build up to a higher one as  your skin gets ‘used to’ the product.

Start with a very low strength product with a maximum concentration of 5% to 10% if you have never used over-the-counter lactic acid before. This will allow you to observe how your skin responds and give your skin time to adjust to the acid.

When is best time to use lactic acid products?

Nighttime is ideal for this ingredient.

Apply lactic acid products exclusively at night. This is crucial since lactic acid and all other AHAs increase the sensitivity of your skin to UV radiation. To safeguard your freshly exfoliated “baby” skin, apply before going to bed and wear sunscreen the next day.

Good to know!

When using lactic acid for the first time, mild stinging and redness are common. Don’t worry; your skin should eventually adjust. If you are struggling to use this product, we’ve got some tips on exfoliating sensitive skin.

How to patch test this skincare ingredient

Before using on your entire face, always test a small area first! You can determine if lactic acid is suitable for your skin by performing a patch test.

  1. In the evening, dab a small amount of the lactic acid product onto your forehead (where your facial skin is thickest).
  2. If there is only mild irritation or no inflammation within 24 hours, apply a thin coating of the lactic acid product in the evening, 1–2 times per week, to your entire face (avoid your eyes!).
  3. If you’ve started on a low percentage of lactic acid (which we recommend), you can start to increase the percentage after a few months of use with little to no irritation or inflammation.

Consider trying another lactic acid product with a lower dose if you have severe irritation within 24 hours (redness, flakiness, peeling).

Side effects

Anyone can have an allergic reaction to anything new, so we highly recommend doing a patch test if you are new to lactic acid. Tinging, redness, and itching are the most common side effects associated with lactic acid. These side effects are usually mild and temporary. If you experience any severe side effects, such as trouble breathing or swelling of your face, lips, tongue, or throat, stop using the product and seek medical attention.

You should avoid applying lactic acid products on the same days as other active ingredients, such as products containing retinol. Instead, you should switch between the two products.



Megan Dominion

Megan Dominion is SILKUP's Managing Editor. She's been down both the curly hair and skincare rabbit holes many times and loves that there's always something new to learn; a new science, method, product or personal experience.