Putting “acid” on your face might sound like a recipe for disastrous stinging, burning, and peeling—a la Samantha’s lobster-red face in that unforgettable episode of Sex and the City. Lactic Acid for your skin is not harsh. It’s one of the least irritating actives around, in fact, and it’s friendly to nearly all skin types.
Along with its gentle nature, it’s also pretty powerful and effective. And the experts we consulted assured us that the standout chemical exfoliant also offers some unique benefits that its counterparts don’t.
To give you a full picture of everything this versatile ingredient has to offer, we asked dermatologists to explain what lactic acid is, what kinds of skin care benefits it can deliver, and some of the best ways to work it into your regular routine—expert-approved product picks included.
What is Lactic Acid?
“Lactic acid is an alpha-hydroxy acid that comes from the fermentation of lactose, a sugar naturally found in milk,” Margarita Lolis, MD, a board-certified dermatologist at Schweiger Dermatology Group in New Jersey, tells SELF. (Don’t worry, the kind used in skin care products is typically synthetically derived, and not from sour milk.)1
Remember that the majority of acids for skin care fall into three different categories: alpha-hydroxy acid (AHA), beta-hydroxy acid (BHA), and polyhydroxy acids. These acids differ in their chemical compositions and benefits. Dr. Lolis points out that lactic is less irritating than its AHA cousins.2 This is largely because it doesn’t sink as deeply into the skin.2
Jeannette G. Graf, MD, an assistant clinical lecturer at Mount Sinai School of Medicine New York City and a board certified dermatologist, told SELF, that glycolic acids, which are also popular alpha hydroxy acids, have a smaller molecule and penetrate deeper and faster. This increases the risk of irritation.2
What is the best way to use lactic acid on your skin?
Lactic acid, however, is a bit of an overachiever, and does more than just what is expected.
Lactic Acid exfoliates.
“Lactic acid works by loosening the ‘glue’ that holds skin cells together, encouraging exfoliation of the dead skin cells and increasing cell turnover,” Dr. Lolis explains.1 She says that this can result in a number of benefits including a more radiant complexion, reduced hyperpigmentation, and dark spots. It also leads to a smoother skin texture and unclogged pore. The fact that it is able to do all this without causing irritation, which can be a problem with stronger ingredients, makes it perfect for those with dry or sensitive complexions.
Both dermatologists SELF consulted said that higher concentrations would be more intense. Dr. Lolis says that most at-home, over-the counter products contain lactic acid in concentrations of 10% or lower. In-office chemical peels typically use a higher percentage of lactic acid. She notes that research shows at 12% it can penetrate deeper into the dermis, the middle layer of skin, potentially minimising the appearance fine lines and wrinkles.3 (Although, especially if you have sensitive, it’s best to talk to a dermatologist before getting any sort of chemical peel to avoid a skin freakout.)
It’s also hydrating.
Here’s where things get interesting. Exfoliating ingredients and moisturizing ones are usually two separate things, correct? That’s not the case with lactic acid. Along with being an exfoliant, it’s also a humectant, meaning it attracts water, for a hydrating and plumping effect, Dr. Graf points out. It’s also worth noting that hyaluronic is a common humectant. That’s another reason why it’s so well-tolerated: Its moisturizing properties help to combat any potential dehydration from the exfoliation, notes Dr. Lolis. This makes it an especially great pick if you’re dealing not only with dullness but also dry skin and flaking.
Antimicrobial properties are also present.
According to Dr. Lolis’s research, lactic acids also have antimicrobial properties. This means that it is able to kill pathogens such as bacteria.4 That’s important because it can help create a balanced microbiome (the combination of billions of microorganisms) on the surface of your skin. What is the result? Less inflammation and a stronger, healthier skin barrier—which can also mean less dryness, Dr. Lolis adds.5