What Is Lactic Acid? 4 Benefits That Make This A Skin Care Fave

When it comes to skin care, most of us have a favorite acid we reach for to tackle our greatest complexion concerns. But if you have sensitive skin, you likely know that slathering any ol' acid over your complexion just isn't a good idea. So if your skin is easily irritated, the best sensitive-skin-friendly acid out there is lactic acid. It can help improve fine lines, reduce breakouts, and exfoliate dead skin. Here, our deep dive. 

When it comes to AHAs, lactic acid has one of the larger molecules in the group, which means it can't penetrate as deeply as others. This means all of the hard work of the acid happens on the surface of the skin, which decreases the amount of irritation and helps to protect the skin barrier. So, no matter whether you have sensitive skin or not, if you've found that other AHAs cause irritation, try swapping for the gentler lactic acid with the same benefits. 

Let's dive into why it's a great addition to your skin care routine. As far as peer-reviewed research goes, there's plenty of evidence to show it's safe and effective—however, it's not as widely studied as some of its other skin care counterparts like glycolic or salicylic acid. That being said, it's overwhelmingly praised by skin care experts.

"Lactic acid is formed by a fermentation process of using bacteria to convert sugars like glucose in lactic acid," Marmur says. "It can be a white powder or a clear liquid and can be formulated with compatible ingredients in serums, creams, cleansers, and chemical peels." And although it is naturally found in dairy products including milk and yogurt, most of the lactic acid we find in topical skin care products is synthetically produced. 

Another issue: AHAs make your skin more sun-sensitive. "There are certain things you use in your routine that make your skin more photosensitive, meaning your skin burns easier, and those include AHAs," says board-certified dermatologist Whitney Bowe, M.D. Marmur also warns that some people find lactic acid makes their skin more sensitive to the sun2, so applying SPF is super important. "Make sure to be extra careful with the sun and use mineral SPF 30 or higher."  

Generally speaking, lactic acid is a great option for those newer to acids or those with sensitive skin. It's gentler than other AHAs and is chock-full of anti-aging benefits. It sloughs off dead skin, decreases hyperpigmentation, balances out moisture levels, and stimulates collagen renewal. And as with all skin care, it's always a good idea to consult with your dermatologist before using.