Read The Label: What You Need To Know About Lactic Acid In Skincare

Feel like you need a dictionary every time you look at the ingredient list of a beauty product? Still unsure of the difference between retinol and retinoids? What about the unique benefits of vitamins B, C, and E? Are alpha and beta hydroxy acids the same thing? The skincare aisle can be overwhelming, but you don’t need a PhD in cosmetic chemistry to navigate it. With expert help, The AEDITION is demystifying and simplifying the beauty industry — one label at a time.

Most of us have been exfoliating for a while now (including that regrettable St. Ives scrub phase), but recent years have seen chemical exfoliators emerge as the favorite over physical exfoliators. Containing ingredients like alpha hydroxy acids (hi, glycolic and mandelic), beta hydroxy acids (read: salicylic acid), and polyhydroxy acids (including gluconolactone), chemical exfoliants work by loosening and removing the bonds between dead skin cells so they slough off, revealing the fresh, glowing skin underneath.

Within the ever-popular crop of AHAs is lactic acid. You may have heard of the gentle-yet-effective active – it is, afterall, one of the more popular exfoliators in the group – but you may not know what makes it special in comparison to its fellow hydroxy acids. To find out more, the AEDITION talked to the experts.

What Is Lactic Acid?

Lactic acid is an organic acid with the molecular formula CH3CH(OH)COOH that is naturally found in sour milk due to the fermentation of sugar and starch, though vegan and manmade versions exist. Lactic acid is also naturally occurring in the body, specifically in the muscles after working out (yep, it’s the cause of that post-sweat session soreness). So, how does this translate to skincare?

The lactic acid found in skincare is generally of synthetic origin. When it comes to skincare, it is “a water-soluble alpha hydroxy acid that exfoliates the surface of the skin to reveal smoother, brighter skin,” explains Shani Darden, a celebrity aesthetician and founder of Shani Darden Skincare. Compared to its counterparts, the lactic acid molecule is larger. “This means that it cannot penetrate the skin as deeply, therefore you're getting more surface-level treatment (polishing, exfoliating, etc.),” she shares. As a result, it is generally considered a milder AHA that can be tolerated by a wider array of skin types.

The Benefits of Lactic Acid in Skincare

One of the reasons hydroxy acids of any kind are so popular is because of their versatility. From dullness to wrinkles to acne, they can tackle an array of skin concerns – and lactic acid is no exception. Lactic acid benefits the skin by:

• Sloughing away accumulated dead skin cells
• Increasing cell turnover
• Removing acne-causing bacteria
• Improving skin tone and texture

But that’s not all. One of the things that differentiates lactic acid from the rest is its gentle nature. Beyond it’s larger molecule size, “lactic acid is less likely than glycolic or salicylic acid to disrupt the pH of your skin,” Darden shares. Perhaps most interesting, it also has an inherent moisturizing factor, “keeping your natural moisture barrier healthy and even adding a little hydration back into the skin,” she adds. This makes it a viable option for sensitive, dry, and more mature skin types.

The Best Candidates for Lactic Acid

While most skin types will benefit from the power of lactic acid’s gentle exfoliation, “individuals who are prone to hyperpigmentation or experience mature skin are great candidates for lactic acid, as it can help fade sun spots or age spots and can smooth and soften fine lines and wrinkles,” explains Jessica Houston, lead aesthetician and vice president of operations at BEAUTYBEEZ.

As for those who should stay away, Audrey Kunin, MD, a board certified dermatologist and founder of DERMAdoctor, notes that those with open wounds or inflamed skin should completely avoid using lactic acid directly on those areas until they are healed. If you have sensitive skin, you probably already know that you should always proceed with caution when adding new ingredients to your skincare routine. Even so, Darden says that all hope is not lost. As we mentioned, the larger molecular size means lactic acid cannot penetrate the skin as deeply. “This is good news for those with sensitive skin, who'll likely be able to tolerate its effects much better than salicylic, glycolic acid, or even retinol,” she explains. In fact, it’s one of the primary reasons she loves the active. “It’s one of my all-time favorite ingredients overall because it’s so effective and can be used by so many skin types,” she notes.

How to Add Lactic Acid to Your Skincare Routine

Lactic acid products usually come in the form of toners, serums, and peel pads, though some creams can also contain the ingredient. Adding it to your routine is a lot simpler than you may think. “Lactic acid is the gentlest of the AHAs, so most people can use it without any problem,” Houston shares. “If you experience any sensitivities, you should incorporate them with another serum or use a dropper to use with a moisturizer.”

Darden agrees that lactic acid is best paired with hydrating products and ingredients – especially if you are new to using it. “When incorporating lactic acid into your routine, you can use an additional hyaluronic acid or moisturizer for added hydration,” she says. But don’t rush the process. “With most lactic acids, you should wait five to 10 minutes before applying [additional layers] so the serum can absorb into the skin without affecting the pH, which could interfere with the efficacy of the treatment,” she cautions.

Ready to add lactic acid to your routine, but don’t know where to begin? Let’s start with serums. Darden recently launched her Lactic Acid AHA Exfoliating Serum, which pairs 9 percent lactic acid with PHA gluconolactone and a proprietary soothing complex to retexturize the skin without irritation. Another editor-favorite on the AEDIT team is the Sunday Riley Good Genes. Packed with purified lactic acid to smooth and clarify, licorice and lemongrass to brighten pigmentation, and prickly pear to calm redness, we like to use it once or twice a week as an overnight treatment. If you are looking for a budget-friendly option, look no further than The Ordinary Lactic Acid 10% + HA, which includes hyaluronic acid for instant hydration. The Biossance Squalane & 10% Lactic Acid Resurfacing Night Serum combines lactic acid with multitasking squalane, which acts as both an emollient and antioxidant.

Since lactic acid is best for exfoliating the top layer of the skin, Dr. Kunin says it can be “used in conjunction with glycolic acid, which is a much smaller molecule and better suited for deeper penetration.” If you decide to go the combination route, Dr. Kunin formulated the DERMAdoctor Ain't Misbehavin' Healthy Toner with Glycolic & Lactic Acid with the pair to help remove excess oil, impurities, and makeup without stripping the skin. The Dr. Dennis Gross Alpha Beta Peel Pads also does the work for you thanks to a hydroxy acid blend that includes lactic, glycolic, and salicylic acids. The SkinCeuticals Clarifying Exfoliating Cleanser, meanwhile, is a dual-chemical and mechanical (courtesy of pumice) exfoliating cream with the duo.

As for how many times a week you should be using lactic acid, it’ll depend on the rest of your routine. While gentle, lactic acid shouldn’t be used at the same time as more aggressive actives like retinol or vitamin C. Even on its own, overuse can lead to a weakened skin barrier. Two to three nights a week is usually a sweet spot for most people, but you can increase or decrease usage after observing how your skin reacts. Short contact therapy might be a good option for those who find they need to ease their way into it.

It’s important to note that lactic acid does affect sun sensitivity. “The acid sloughs away skin cells, it leaves your skin more likely to be damaged by ultraviolet light,” Houston warns. As such, reserve lactic acid for your P.M. routine and be sure to be extra diligent with your sunscreen application the morning after.

The Takeaway

Lactic acid is a popular AHA that can brighten dull skin, fade sun spots, and increase cell turnover. It’s gentle enough to use for most skin types, and it’s considered to be easier on the skin than fellow hydroxy acids like salicylic and glycolic. Too much of a good thing can be, well, not good, so don’t go overboard with your usage. Stick to a couple times a week and watch your complexion glow.

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