Everything You Need To Know About Lactic Acid
Despite (or maybe because of) being founded by a Swedish chemist over 200 years ago, lactic acid is still a highly sought-after ingredient in the skincare space. ‘’It is one of the most common ingredients in both OTC and professional formulations,” agrees Diana Yerkes, Lead Esthetician and Educator at Rescue Spa NYC. Derived from the Latin word ‘lac’, it’s a natural preservative found in fermented foods such as yogurt and milk. (Some can even argue it got its informal start as a skincare remedy in ancient Egypt, where Cleopatra was known to bathe in sour milk as a beauty ritual.)
WHAT IS LACTIC ACID?
‘’Lactic acid is an alpha hydroxy acid (AHA) that works by breaking down the bonds between skin cells, which helps shed away the dead layers of skin,” says cosmetic and skincare expert Dr. Ana Mansouri. In other words, lactic acid is an efficient chemical exfoliant that melts away old skin cells to reveal a fresh, rejuvenated complexion. That’s why this AHA is included in our Daily Brightening Toner, a powerful yet gentle solution that targets hyperpigmentation and clogged pores.
HOW DOES LACTIC ACID BENEFIT THE SKIN?
Lactic acid has been hailed as a non-irritating option that benefits all skin types—even sensitive and acne-prone ones. ‘’Due to its relatively large molecules, lactic acid doesn’t penetrate deeply into the layers of the skin, so it can remove superficial layers without irritating the deeper ones,” Dr. Mansouri says. It’s so gentle, complexions with eczema and rosacea can even use it.
Lactic acid also has a reputation for combating discoloration, like dark spots. ‘’It is known as a mild tyrosinase inhibitor which can slow down the formation of the pigment granules,” says licensed esthetician Biba de Sousa. Its abilities go beyond brightening, however. Incorporate this AHA into your routine if any of these concerns apply to you:
- Dull and/or uneven skin tone
- Dark spots and post-acne marks
- Clogged pores and acne
- Rough, bumpy skin texture
- Premature fine lines and sagging skin
HOW TO APPLY LACTIC ACID
Lactic acid can be found in all kinds of skincare, from cleansers and toners to masks and overnight treatments, such as The Shortcut. No matter which form you use, consistent application is key. ‘’Lactic acid should be used regularly, either all over the face or on specific areas, but if you notice any irritation, stop using the product,” says board-certified dermatologist Dr. Anna Chacon. Don’t forget about body care, too. Exfoliating areas like the legs, shoulders, and bum can reduce the appearance of keratosis pilaris (a.k.a. “chicken skin”), brighten age spots, and prevent body acne. Get these results with our Buff It Out AHA Exfoliating Body Scrub.
Like other AHAs, we suggest reserving lactic acid for your PM routine. “Lactic acid’s strong exfoliative properties weaken cellular bonds which can lead to UV damage,” Dr. Chacon adds. If you do apply during your morning routine, make sure to follow up with a broad-spectrum mineral SPF, such as Guards Up.
Generally speaking, experts recommend exfoliating 1-3x per week. Low concentrations of lactic acid, however, can be applied nightly. Always follow the “How to Use” instructions written on the back of the formula’s packaging and consider patch testing if you’re ultra-sensitive.
WHAT INGREDIENTS DO NOT MIX WELL WITH LACTIC ACID?
Because it's so gentle, lactic acid can be layered over most other skincare ingredients. ‘’Lactic acid works well when combined with other AHAs, BHAs, and TCAs,” adds de Sousa. You’ll find a blend of skin-safe acids in our Doctor’s Visit Instant Resurfacing Mask. Lactic acid also plays kindly with non-actives, such as niacinamide and hyaluronic acid.
The only skincare ingredient to avoid using with lactic acid is retinol. “Both ingredients [can be] very potent, so alternate between the two to avoid irritation,” says Yerkes.
Shop lactic acid skincare below.