Everything You Need to Know About Lactic Acid, the Ultimate Skin Brightening Ingredient
If you've ever dealt with patches of dry, rough skin, then you know that exfoliating is no easy feat. However, with so many physical and chemical exfoliants out there, there's plenty to choose from, although admittedly it can be hard to decide. Ingredients like citric, glycolic, and lactic acid are all great options when choosing a gentle chemical exfoliant—all are versions of alpha-hydroxy acids (AHAs)—but there's one that all dermatologists recommend for a bright complexion.
Lactic acid is a skincare ingredient that everyone seems to be talking about due to its transformative results—but, if it's your first time using lactic acid, there are a few things you should know before incorporating it into your skincare routine. To share the best practices on how to use lactic acid, we rounded up the expert advice of three board-certified dermatologists: Elyse Love, M.D., Tiffany Libby, M.D., and Robyn Gmyrek, M.D.
What is lactic acid?
Dr. Libby explains that lactic acid is an alpha-hydroxy acid and one of the gentlest chemical exfoliants available. "It is a larger molecule than the well-known glycolic acid, also an AHA, so it does not penetrate skin layers as deeply—which gives it a more shallow and uniform skin penetration–making it more gentle and ideal for more sensitive skin types."
Dr. Gmyrek further explains that it's naturally found in milk and is the reason that, as legend has it, Cleopatra used to take milk baths as it softened her skin. "It is primarily used as a humectant in moisturizers to help draw water into the skin and as a regulator of pH, or the level of acidity, in a product."
What are some benefits of lactic acid?
Lactic acid buffs away dead skin cells which, in turn, brightens skin and unclogs pores. Dr. Gmyrek explains that when it's combined with moisturizing ingredients it also allows for increased absorption (of other products) and skin hydration. Additionally, she shares that it can treat keratosis pilaris (strawberry skin), sun-induced hyperpigmentation, and melasma.
That's not all this AHA does. "Lactic acid is also antibacterial and helps treat acne," says Dr. Libby, adding that it also increases skin cell turnover, improves skin texture, and minimizes the appearance of fine lines.
Who should use lactic acid?
It's a great exfoliating option for most people, says Dr. Love, "especially those with sensitive skin since it's one of the gentlest alpha hydroxy acids." Dr. Love recommends using lactic acid before moisturizing ingredients to allow deeper penetration of the moisturizer. "This can be in the form of a cleanser, toner, serum, or treatment mask/peel."
Dr. Libby recommends using it at night so it can exfoliate and slough off dead skin cells with sensitizing it too much to the sun. However, she says you still need to use SPF in the morning. "Lactic acid leaves the newer skin more susceptible to the sun, so make sure to use SPF while using exfoliant products to protect your skin."
How often should you use lactic acid?
When you first start using it, explains Dr. Libby, use it two-three times a week to start to see if your skin can handle it. "If you notice you can tolerate it, it's gentle enough to use it nightly." It also depends on the product formulations, as Dr. Love explains that some products are designed to be used daily, while others are designed to be used on a weekly or biweekly basis. "Those with sensitive skin should always start slow to prevent possible irritation."
What skincare ingredients pair well with lactic acid?
Lactic acid can be incorporated into any skincare routine easily. Dr. Libby says that she loves lactic acid paired with squalane and hyaluronic acid to help improve its tolerability, allowing for both exfoliation and hydration of the skin. "The only products I would say you really should pair with lactic acid are a moisturizer and a sunscreen," adds Dr. Gmyrek. She says moisturizer will maximize the benefits of lactic acid when used together.
What skincare ingredients shouldn't be mixed with lactic acid?
Although lactic acid pairs well with almost all skincare ingredients, Dr. Love cautions against layering multiple skincare acids as it could increase the risk of skin irritation. According to Dr. Gmyrek, it's best to use the following ingredients with caution: retinoids including tretinoin, physical scrubs, retinol, and other acids.
Are there side effects from using lactic acid?
Excessive use of lactic acid can lead to dryness, redness, irritation, and a cracked and unhealthy skin barrier, explains Dr. Gmyrek. "When the skin barrier or outer layer is compromised, there are microscopic breaks in the skin, moisture is lost through these cracks to the environment and the openings allow chemicals and bacteria into your body," she says. Lactic acid, like other exfoliating agents, help exfoliate and slough off dead skin cells, so it leaves the skin more susceptible to the sun. (Make sure to use SPF!)
Best skincare products with lactic acid:
Best serum with lactic acid: Sunday Riley
Dr. Love recommends this lactic acid serum as it's a great gentle alternative for glycolic acid for sensitive skin. It can also be used daily (or weekly, if you prefer) and is safe for pregnant women.
Best face mask with lactic acid: Drunk Elephant
Recommended by Dr. Gmyrek, this weekly treatment combines a wide array of fantastic ingredients—like lactic, glycolic, citric, hyaluronic acid, and niacinamide—to help improve discoloration, stimulate collagen, and minimize acne.
Best toner with lactic acid: Glossier
Composed of salicylic, lactic, and glycolic acid, this lighter formula is ideal for everyday usage. It's also great for the improvement of mild acne, says Dr. Love.
Best lactic acid peel: Obagi
This at-home peel can provide a noticeable improvement in skin texture with its high concentration of salicylic, lactic, and glycolic acid.
Best moisturizer with lactic acid: SkinBetter
Dr. Gmyrek and Dr. Libby both recommend this overnight cream since it combines lactic acid with peptides, niacinamide, antioxidants, and a retinoid in one product. It was scientifically studied for effectiveness and was found to reduce fine lines, unwanted pigmentation, the appearance of pore size, and redness.
Best body scrub with lactic acid: First Aid Beauty
This exfoliator is fantastic for getting rid of Keratosis Pilaris—it even freed one of our writers from her lifelong battle with ingrown hairs. It's gentle, easy-to-use, and is affordable. Plus, it's a favorite of Dr. Love, so you know it's going to be good.
Best body lotion with lactic acid: AmLactin
This thick and creamy moisturizer contains 12% lactic acid to exfoliate dead skin while moisturizing it as well. Dr. Gmyrek has been recommending this product to her patients for years due to its amazing results and price point.