Skin care can be an investment. When it comes to the products you're slathering all over your face, you want to ensure you're getting an efficacious formula that's suitable for your individual skin type and makes sense for your goals. That comes down to knowing what different skin-care ingredients are and what they can do for your skin.
Do you want to keep new breakouts at bay? Get that glowy, glass-like complexion that you see all over Instagram? Restore some moisture to your dry skin? There's an ingredient for that — and the key is knowing which one is right for the task at hand. So, pull up a chair and get ready for your latest skin school lesson on lactic acid.
This gentle skin-care acid is from the alpha-hydroxy acid family and is great for targeting everything from dark spots to dullness and wrinkles. Want to know more? Keep reading to learn more about lactic acid from two board-certified dermatologists.
What Is Lactic Acid?
When talking about skin care, lactic acid is an alpha hydroxy acid, otherwise known by its abbreviation, AHA. But you may also be familiar with the lactic acid your body produces as a chemical when your cells break down carbohydrates. In beauty products, it can be derived from milk, as you may have guessed, but there are also alternatives made from plants or biotechnology.
"It is hydrophilic, meaning that it mingles well with water, but not as well with oil," Brendan Camp, MD, who is double board-certified in dermatology and dermatopathology, tells POPSUGAR. "As a result, lactic acid tends not to penetrate deeply in the skin, making it a more gentle exfoliating acid."
Corey L. Hartman, MD, FAAD, board-certified dermatologist and founder of Skin Wellness Dermatology, adds: "It is one of the gentler alpha hydroxy acids, so it's a good one to start with if you are interested in the benefits of AHAs but haven't tried one before." It's well-tolerated by all skin types, including those with sensitive skin.
Lactic Acid's Benefits: What Does Lactic Acid Do?
Lactic acid's benefits are on par with other AHAs. Primarily, it's used for brightening the skin's overall tone, but that's not all it does. "[It's] commonly found in skin-care products designed to brighten and reduce the appearance of dark spots, as well as reduce the appearance of fine lines and wrinkles," says Dr. Hartman.
That's only the beginning: Dr. Camp says that it's also used to treat keratosis pilaris, which causes bumpy, tiny red spots on the skin. "Lactic acid also helps thicken the skin and stimulates the production of collagen in the body, which helps add plumpness and reduce the appearance of fine lines and wrinkles," Dr. Hartman says.
It works by removing dead skin cells at the surface by dissolving the bonds that hold them together. This "facilitates the body's natural exfoliating process," says Dr. Camp. As a result, new cells grow, resulting in smoother, brighter skin.
How to Use Lactic Acid
Lactic acid has become fairly popular in recent years, making it easy to find in the skin-care aisle. "Lactic acid may be featured in a number of different skin-care products, including cleansers, moisturisers, peels, and serum," says Dr. Camp. Toners and serums are the most common.
Acids are usually included in formulations at different percentages, with a higher percentage meaning it's a more potent dose. "Look for a skin-care product with lactic acid as one of its main ingredients in a percentage between five percent for a beginner to up to 15 to 20 percent for someone who has used the ingredient before," Dr. Hartman says.
You should always follow the instructions on the packaging when it comes to how often to use a product, but typically, people fold it into their skin-care routine one to three times a week. And every morning, make sure to apply your daily face sunscreen since "lactic acid can potentially make skin more sun sensitive," says Dr. Camp.
Using Lactic Acid on Dark Skin
Treating hyperpigmentation on darker skin can be tricky, but lactic acid is especially good for it. "Patients with dark skin have more melanin than those with lighter skin, and when dark skin is irritated by a harsh acid, it may trigger an immune response, which leads to hyperpigmentation," says Dr. Hartman. "Lactic acid is gentler, so it has less of a risk of triggering that reaction."
Using Lactic Acid With Other Skin-Care Ingredients
Even though lactic acid is fairly gentle, it is still an acid and should be treated as such. When it comes to mixing ingredients, proceed with caution. "[It] can potentially irritate skin and cause redness, dryness, peeling, or itching," says Dr. Camp. That said, it shouldn't be mixed with other potentially irritating ingredients like glycolic acid, salicylic acid, benzoyl peroxide, and retinoids.
Outside of other AHAs and BHAs, Dr. Hartman also says, "Don't mix lactic acid with vitamin C, as the lactic acid will lower the pH of the vitamin C and make it ineffective. I also would not mix niacinamide and lactic acid for the same reason; their differing pH levels will render both lactic acid and niacinamide useless."
If you really want to use lactic acid with another exfoliant, you need to be strategic about it. "Switch them during the week," says Dr. Hartman. "Use a lactic acid product one day and then the retinol the next day." Or, look for products that are specifically formulated with the ingredients you're hoping to combine.
Who Shouldn't Use Lactic Acid
Both doctors say that even though lactic acid is generally well-tolerated by those with sensitive skin, if you're extremely sensitive, you should be careful. "Avoid the use of lactic acid on skin that is irritated or inflamed, like a sunburn," says Dr. Camp. Like with most ingredients, it's best to do a spot test 24 hours before to check your tolerability.
Those who are using isotretinoin (Accutane) or other prescription topicals, especially for acne, should consult with a dermatologist before incorporating the ingredient into their routine. "I don't advise using harsh acids while intensively treating acne," says Dr. Hartman, adding: "Lactic acid is generally considered safe to use during pregnancy, though speak to your obstetrician to confirm."