COSRX Low pH BHA Overnight Mask


Low pH BHA Overnight Mask

1.69 fl. oz. for $ 21.00
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Brand Overview

COSRX’s Low pH BHA Overnight Mask is a creamy, soothing face mask that feels great, but doesn’t have quite the potent benefits the brand claims.

Packaged in an opaque squeeze tube that protects its light- and air-sensitive ingredients, this fragrance-free cream is rich yet lightweight, though it’s best for those with normal, dry, and combination skin (those with very oily skin might find this too moisturizing). Application is smooth and even, and it absorbs quickly into skin for an immediate smoothing effect.

This is in part due to the moisturizing ingredients present: sunflower seed oil, glycerin, and some fatty alcohols. All of these will serve to help preserve skin’s moisture barrier. There’s also antioxidant centella asiatica water, some lactic acid (which has hydrating benefits), and skin-brightening niacinamide.

There are a couple of points to address about the product’s name. First, this does have a relatively low pH of 4.01, which means it’s slightly below the pH of skin (which averages 4.7). While that’s a positive trait, it’s not unique to this product; most skin care products are within this range (except for most bar soaps!)

The second point is that the 0.9% BHA in this product’s claims isn’t pure salicylic acid, which is what most consumers think of when they hear the term “BHA.” Instead, it’s betaine salicylate. There is some research (though not a great deal) showing that it can have exfoliation benefits as well, but so far, we haven’t seen any definitive study demonstrating its effects are comparable. The optimal concentration for any exfoliation to occur for this ingredient is higher than the 0.9% present here (4% is supposed to be the equivalent of 2% BHA). Though you’re likely to get some mild exfoliation benefits, it would be more effective in a higher amount, especially since it’s also within the optimal pH of between 3.8 and 4.2 for exfoliation to occur.

This isn’t to say it’s a bad ingredient, it’s just that it doesn’t have quite the “polishing” effect on skin that salicylic acid does as claimed. It’s just something to keep in mind when considering this product’s claims.

With that in mind, this is still a worth considering (like salicylic acid, betaine salicylate is also anti-inflammatory), it’s just important that you keep your expectations realistic!

  • Cream is rich yet lightweight.
  • Contains ingredients to preserve skin’s moisture barrier.
  • Contains antioxidant and skin-brightening ingredients.
  • Betaine salicylate has potential mild exfoliating benefits.
  • Packaged to protect its light- and air-sensitive ingredients.
  • Betaine salicylate doesn’t have the depth of research showing it can act exactly like BHA in skin care.
Jar Packaging: No
Tested on animals: No

Low pH BHA Overnight Mask polishes away dullness and reveals your soft skin during the night. 0.9% BHA will help to reduce roughness and make skin complexion look healthier.

Centella Asiatica Leaf Water, Butylene Glycol, Helianthus Annuus (Sunflower) Seed Oil, Glycerin, Betaine, Panthenol, Cetearyl Alcohol, Dimethicone, Elaeis Guineensis (Palm) Oil, Elaeis Guineensis (Palm) Kernel Oil, Beeswax, Gluconolactone, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Cetearyl Olivate, Sorbitan Olivate, Caprylic/Capric Triglyceride, 1,2-Hexanediol, Betaine Salicylate, Ethylhexylglycerin, Lactic Acid, Water, Niacinamide, Xanthan Gum, Sodium Hydroxide, Ethyl Hexanediol, Melaleuca Alternifolia (Tea Tree) Leaf Oil.

COSRX is one of a growing number of Korean beauty brands – a category known by many simply as K Beauty – that’s gaining a foothold in the Western cosmetics world. COSRX got its start in 2014, though it’s essentially an offspring of older “sister” brands, including C20 and Gatzmen, which have longer-standing histories in the Korean market. As the story goes, COSRX came about after the parent company compiled a decade’s worth of research based on customer data and beauty consumer research.

The brand name, as you might have guessed, is a mash-up of “cosmetics” and “RX” (for prescription), and illustrates COSRX’s overall philosophy. Whereas some other K-beauty brands are known for whimsical packaging and brightly-colored products, CosRX’s focus is minimalistic packaging and products designed to target specific skin care concerns, each highlighted by active ingredients.

To that end, the brand is largely successful. Most of the packaging is designed to protect light- and air-sensitive ingredients, though there are some jars in the mix. The formulas focus on active ingredients such as alpha hydroxy acids, hyaluronic acid, and beta hydroxy acid (though it should be noted, COSRX uses BHA derivatives, since salicylic acid’s use is restricted in Korea).

Most of the exfoliants are formulated at the optimal pH for exfoliation, which is between 3 and 4, and are fragrance free. Unfortunately there are some formulas that include natural ingredients that can potentially sensitize skin, including pine and cedar extracts, and anise fruit extract – proof once again that natural isn’t always better! Some products also contain drying alcohol, which is interesting since other products are specifically advertised as being “alcohol-free.”

Overall, this line is worth considering, especially if you prefer a more targeted approach to skin care that focuses on science rather than trends. For more information, visit, the brand’s official Korean site. COSRX is available for purchase at several U.S. and online retailers, including Ulta, Amazon, and SokoGlam.

About the Experts

The Beautypedia team consists of skin care and makeup experts personally trained by the original Cosmetics Cop and best-selling beauty author, Paula Begoun. We’re fascinated by skin care and makeup products and thrilled when they meet or exceed our expectations, but we’re also disappointed when they fail to perform as claimed, are wildly overpriced, or contain ingredients scientific research has proven can hurt skin.

Our mission has always been to help you find the best products for your skin, no matter your budget or preferences. Beautypedia’s thorough and insightful reviews cut through the hype and provide reliable recommendations for all ages, skin types, and skin tones.

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