Type of ingredient: Acid/exfoliator
Main benefits: Firmer, thicker skin, resulting in fewer fine lines, wrinkles, and acne lesions
Who should use it: In general, anyone with acne-prone skin or who frequently breaks out.
How often can you use it?: It's only recommended for use once a day at maximum, but should probably be used once every few days.
Works well with: Hydrating ingredients like hyaluronic acid
Donâ€™t use with: Other acids and exfoliants like AHAs or benzoyl peroxide. Retinol should be avoided as well.
What Is Lactic Acid?
Swedish chemist Carl Wilhelm Scheele was the first to isolate the compound from sour milk, and in the late 1800s, German pharmacist Albert Boehringer uncovered how to mass-produce lactic acid when he realized it was a byproduct of fermented sugar and starch in sour milk via bacteria. "Lactic acid is a light peeling agent, depending on strength," says MacGregor. She also notes that it "can smooth out the skin, making it glow." You can find lactic acid in many of the same places other alpha hydroxy acids (AHAs) are found, including products that advertise that they contain AHAs but don't specify which ones they contain.
Lactic Acid vs. Other Acids
If you're wondering how it differs from other acids, like, say, glycolic acid, the lactic acid molecule is actually larger, so it can't penetrate as deeplyâ€” instead, you're getting more surface treatment (polishing, firming, exfoliating goodness). This is good news for those with sensitive skin, though, who'll likely be able to tolerate its effects better. This isn't just good news for people with sensitive skin, though, because it means lactic acid is also less likely than glycolic or salicylic acid to cause irritation and disrupt the pH of your skin barrier. So pretty much anyone can use it. If you're someone with acneic skin who needs a lot of exfoliation, you can alternate your use of lactic acid with the use of something deeper like salicylic, which will clear off dead skin and deep clean your pores.
Side Effects of Lactic Acid
As with any acid, it's important to use it wisely. "Do not use on irritated or red skin!" MacGregor warns. Using too much of any one acid too often can lead to inflammation, which accelerates the aging process. Using too much at once can also lead to inflammation orâ€”worseâ€”rashes and chemical burns. It is worth noting, though, that lactic acid actually does irritate skin less than many other acids, and therefore, can be used more often than something like (the very intense) salicylic acid.
How to Use It
Celebrity esthetician RenÃ©e Rouleau recommends incorporating a lactic acid product (like a serum or toner) on a three-on/three-off schedule, i.e., you should apply the acid for three nights in a row, then take a break for three nights to treat your skin with hydrating ingredients that nourish the new cells you've revealed.
Also, consider discontinuing strong exfoliating products such as retinoid or scrubs when you're regularly using lacticâ€”or anyâ€”acid. "As it makes new skin grow, which may not have any pigment in it, it may cause increased susceptibility to sunburn. Therefore, it is often formulated with sunscreen," says Schep. Since sloughing off layers of your skin also leaves you more prone to sun damage, make sure to apply an SPF of at least 30 daily (as you should be, anyway!).
The Best Products With Lactic Acid
ishonest's former editorial director says this scrub with exfoliating alpha- hydroxy acids (like lactic) makes her "forget" she has keratosis pilaris (a condition where your skin has little tiny bumps, usually on the backs of the arms and thighs) for at least two days.
A personal favorite of this editor, this tonic is safe enough to use daily on clean skin. The result is that sort of cherubic glow you can only achieve after a facial.
Lactic acid doesn't have to be reserved for the skin on your face and body. It's also excellent for the scalp, where it may exfoliate flakiness and strengthen the hair follicle. We love this particular shampoo for its invigorating scent and powerful cleanness.
Touted as "the Hollywood two-minute facial," this pore-unclogging treatment uses lactic acid and fruit enzymes to vacuum out congestion, leaving behind a smooth, bright complexion you'd think were only achievable by the hands of an esthetician.
For those who aren't familiar, squalane is a super-nourishing and incredibly clean oil that Biossance works into all its products. This is particularly helpful when paired with exfoliators, which take a bit of a toll on the skin. Although you might find yourself using the brand's Squalane + Phyto Retinol Serum ($72) at night, this is a gentler exfoliating serum you can use during the day. (With SPF, of course).
Britannica. Carl Wilhelm Scheele.
Boehringer Ingelheim. 1885-1948: Innovative beginnings.
Naval T, Aligui G, Rivera E. A study of bacterial skin colonization among newborn infants using lactic acid and hexachlorophene. Phil J Microbiol Infect Dis. 1985;14(2): 55-57.
Soleymani T, Lanoue J, Rahman Z. A practical approach to chemical peels: a review of fundamentals and step-by-step algorithmic protocol for treatment. J Clin Aesthet Dermatol. 2018;11(8): 21-28.
Read more on: skin