Sour Milk Skincare? Here’s How Lactic Acid Gives Your Skin a Major Glow-Up

Mia Maguire
Sour Milk Skincare? Here’s How Lactic Acid Gives Your Skin a Major Glow-Up
Photo: Sunday Riley.

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Spoiled milk probably sounds like the last thing you want to put on your face, right? Well, it turns out it’s actually pretty beneficial. Yet another addition to the bizarre (yet effective) skincare ingredient canon, lactic acid—a natural exfoliating acid found in rotten milk—is actually a mild Alpha Hydroxy Acid (AHA) that improves texture, nixes hyperpigmentation and scars, and soften the appearance of fine lines. Unlike many members in the AHA family, lactic acid is a much more gentle agent, allowing you to reap the unparalleled anti-aging benefits you’ll get from, say, a glycolic acid, but with much more gradual results and therefore, less irritation, peeling, and redness.

The best part is that you don’t have to douse your face in decaying milk to take advantage of the acid’s substantial laundry list of complexion-enhancing properties—I mean, that would be ridiculous; not to mention downright gag-worthy. Fortunately, savvy skincare brands have taken note of this under-the-radar acid’s multifaceted beauty virtues. Aside from exfoliating away dead skin cells and accelerating cell turnover exponentially, lactic acid also helps kill breakout-inducing bacteria, helping you maintain clear skin. It also helps improve skin’s elasticity with continuous use, and because it sloughs away impurities from the dermis, it also helps your subsequent skincare products absorb better (read: work better). Ready to add some sour-milk-spiked skincare to your current beauty lineup? If so, scroll through below to check out some of our favorite formulas to try for yourself.

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1. The Ordinary Lactic Acid 10% + HA

the ordinary lactic acid serum

The Ordinary.

This lactic acid-based peel is also infused with skin-plumping and hydration-boosting Hyaluronic Acid to help offset any potential irritation from the exfoliation process. It leaves the skin feel smooth, looking brighter and feeling hydrated. The concentrated formula also contains Tasmanian pepper berry, which helps to soothe inflammation and irritation associated with acids.

2. Theraderm Fruit Acid Exfoliant

Theraderm Fruit acid peel


Containing unbuffered (i.e. more pure) lactic acid, this gentle, yet effective fruit-derived formula evens out discoloration, refines enlarged pores, and helps to fade sun spots and scarring. The natural exfoliating solution is also free of sulfates, parabens and synthetic chemicals. It’s even gentle enough to apply to the eyelids.

3. Sunday Riley Good Genes All-in-One Lactic Acid Treatment

Sunday Riley Good genes amazon

Sunday Riley.

This targeted lactic acid treatment gives your skin a deep detox with just one application. It exfoliates the skin to get rid of impurities that clog your pores and create uneven texture. The formula is also infused with licorice root to combat dullness and lemongrass to even out hyperpigmentation.